Solve Quadratic Equations: $2x^2-2x-12=0$

by Andrew McMorgan 42 views

Today, we're diving deep into the fascinating world of quadratic equations, specifically tackling the beast that is 2x2βˆ’2xβˆ’12=02x^2 - 2x - 12 = 0. If you're looking to understand the number and type of solutions this equation holds, you've come to the right place. We're going to break it down, step-by-step, making sure you grasp every bit of it. Forget those dry textbooks; we're here to make math make sense, and maybe even a little fun! So, grab your calculators, your notepads, and let's get ready to unravel the mysteries hidden within this quadratic expression. We'll explore different methods to find the solutions, discuss why certain types of solutions arise, and ultimately, figure out exactly what kind of answers we're dealing with. Get ready to boost your math game!

The Discriminant: Your Key to Solution Types

Alright, fam, let's talk about the discriminant, which is basically your magic key to figuring out the number and type of solutions to any quadratic equation in the standard form ax2+bx+c=0ax^2 + bx + c = 0. This little powerhouse is calculated as Ξ”=b2βˆ’4ac\Delta = b^2 - 4ac. Why is it so important? Because the value of the discriminant tells us everything we need to know about our solutions without even having to solve the equation fully! If Ξ”>0\Delta > 0, you're looking at two distinct real solutions. This means your parabola crosses the x-axis at two different points. Think of it as getting two unique, solid answers. Now, if Ξ”=0\Delta = 0, you've hit the jackpot with exactly one real solution. This is often called a repeated or double real root, where the parabola just touches the x-axis at its vertex – like a perfect kiss. Finally, if Ξ”<0\Delta < 0, brace yourselves, because you're dealing with two complex or imaginary solutions. These solutions come in a conjugate pair, meaning they have a real part and an imaginary part (aΒ±bia \pm bi). In this case, the parabola doesn't touch the x-axis at all; it either hovers above or below it. Understanding the discriminant is super crucial because it gives you a shortcut to classifying your answers before you even get bogged down in calculations. For our specific equation, 2x2βˆ’2xβˆ’12=02x^2 - 2x - 12 = 0, we can identify a=2a=2, b=βˆ’2b=-2, and c=βˆ’12c=-12. Plugging these into the discriminant formula, we get Ξ”=(βˆ’2)2βˆ’4(2)(βˆ’12)\Delta = (-2)^2 - 4(2)(-12). Let's crunch those numbers: (βˆ’2)2(-2)^2 is 44, and βˆ’4(2)(βˆ’12)-4(2)(-12) is βˆ’8(βˆ’12)-8(-12), which equals 9696. So, Ξ”=4+96=100\Delta = 4 + 96 = 100. Since 100>0100 > 0, we already know we're in for two distinct real solutions. Boom! Just like that, the discriminant has given us the lowdown. No need to guess or get confused; this is your reliable guide to the nature of the roots. So, whenever you encounter a quadratic equation, remember to lean on the discriminant. It's your best friend for quickly analyzing the solution landscape.

Simplifying the Equation: Making Life Easier

Before we jump into solving 2x2βˆ’2xβˆ’12=02x^2 - 2x - 12 = 0 directly, let's talk about making things a bit cleaner. Often, quadratic equations come with coefficients that share a common factor. In our case, the numbers 22, βˆ’2-2, and βˆ’12-12 are all divisible by 22. Simplifying the equation by dividing every term by this common factor can make subsequent calculations much less of a headache. So, if we divide the entire equation 2x2βˆ’2xβˆ’12=02x^2 - 2x - 12 = 0 by 22, we get: (2x2)/2βˆ’(2x)/2βˆ’12/2=0/2(2x^2)/2 - (2x)/2 - 12/2 = 0/2. This simplifies to x2βˆ’xβˆ’6=0x^2 - x - 6 = 0. Now, this new equation, x2βˆ’xβˆ’6=0x^2 - x - 6 = 0, is equivalent to our original one; it will have the exact same solutions in terms of their nature and value. Why bother? Because working with smaller numbers, like 11, βˆ’1-1, and βˆ’6-6 instead of 22, βˆ’2-2, and βˆ’12-12, significantly reduces the chances of making arithmetic errors, especially when you're using methods like the quadratic formula or factoring. It’s a little trick that seasoned math folks use all the time to keep things manageable. Think of it like decluttering your workspace before starting a big project – it just makes everything flow better. So, for x2βˆ’xβˆ’6=0x^2 - x - 6 = 0, our new a=1a=1, b=βˆ’1b=-1, and c=βˆ’6c=-6. If we were to re-calculate the discriminant using these simplified coefficients, we'd get Ξ”=(βˆ’1)2βˆ’4(1)(βˆ’6)=1βˆ’(βˆ’24)=1+24=25\Delta = (-1)^2 - 4(1)(-6) = 1 - (-24) = 1 + 24 = 25. Since 25>025 > 0, we again confirm that we're dealing with two distinct real solutions. See how much easier it is to work with these numbers? Simplifying upfront is a pro move that pays off big time, ensuring accuracy and saving you precious brainpower for the actual problem-solving. It’s a fundamental step that many overlook, but it’s absolutely key to efficient and error-free math.

Method 1: Factoring Your Way to Solutions

Now that we've simplified our equation to x2βˆ’xβˆ’6=0x^2 - x - 6 = 0, one of the most straightforward ways to find the number and type of solutions is through factoring. This method works beautifully when the quadratic expression can be broken down into two binomials. We're looking for two numbers that multiply to give us cc (which is βˆ’6-6 in our simplified equation) and add up to give us bb (which is βˆ’1-1). Let's brainstorm some pairs of factors for βˆ’6-6: (1,βˆ’6)(1, -6), (βˆ’1,6)(-1, 6), (2,βˆ’3)(2, -3), and (βˆ’2,3)(-2, 3). Now, let's check their sums: 1+(βˆ’6)=βˆ’51 + (-6) = -5, βˆ’1+6=5-1 + 6 = 5, 2+(βˆ’3)=βˆ’12 + (-3) = -1, and βˆ’2+3=1-2 + 3 = 1. Bingo! The pair (2,βˆ’3)(2, -3) adds up to βˆ’1-1. This means we can factor our quadratic expression x2βˆ’xβˆ’6x^2 - x - 6 into (x+2)(xβˆ’3)(x + 2)(x - 3). So, the equation x2βˆ’xβˆ’6=0x^2 - x - 6 = 0 becomes (x+2)(xβˆ’3)=0(x + 2)(x - 3) = 0. For this product to be zero, at least one of the factors must be zero. This gives us two separate possibilities: either x+2=0x + 2 = 0 or xβˆ’3=0x - 3 = 0. Solving the first equation, x+2=0x + 2 = 0, we subtract 22 from both sides to get x=βˆ’2x = -2. Solving the second equation, xβˆ’3=0x - 3 = 0, we add 33 to both sides to get x=3x = 3. So, our solutions are x=βˆ’2x = -2 and x=3x = 3. These are both real numbers, and they are distinct (different from each other). This confirms our earlier findings using the discriminant – we have two real solutions. Factoring is a really satisfying method when it works because it directly reveals the roots. It’s like unlocking a code! If factoring seems tricky, don't sweat it; there are other powerful methods we can use, like the quadratic formula, which always works, regardless of whether the expression is easily factorable or not. But when factoring clicks, it's incredibly efficient and gives you that neat 'aha!' moment.

Method 2: The Quadratic Formula - Your Universal Solver

When factoring feels like a puzzle you can't quite crack, or you just want a surefire way to get the job done, the quadratic formula is your ultimate hero. This formula is derived from completing the square and works for any quadratic equation in the form ax2+bx+c=0ax^2 + bx + c = 0. The formula is: x=βˆ’bΒ±b2βˆ’4ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}. Remember that b2βˆ’4acb^2 - 4ac part? That's our old friend, the discriminant! So, the formula is essentially built upon it. Let's use our simplified equation x2βˆ’xβˆ’6=0x^2 - x - 6 = 0, where a=1a=1, b=βˆ’1b=-1, and c=βˆ’6c=-6. Plugging these values into the quadratic formula, we get: x=βˆ’(βˆ’1)Β±(βˆ’1)2βˆ’4(1)(βˆ’6)2(1)x = \frac{-(-1) \pm \sqrt{(-1)^2 - 4(1)(-6)}}{2(1)}. Let's simplify step-by-step: x=1Β±1βˆ’(βˆ’24)2x = \frac{1 \pm \sqrt{1 - (-24)}}{2}. This becomes x=1Β±1+242x = \frac{1 \pm \sqrt{1 + 24}}{2}, which simplifies further to x=1Β±252x = \frac{1 \pm \sqrt{25}}{2}. Now, we know that 25=5\sqrt{25} = 5. So, we have x=1Β±52x = \frac{1 \pm 5}{2}. This gives us two possibilities, one for the plus sign and one for the minus sign: x1=1+52=62=3x_1 = \frac{1 + 5}{2} = \frac{6}{2} = 3 and x2=1βˆ’52=βˆ’42=βˆ’2x_2 = \frac{1 - 5}{2} = \frac{-4}{2} = -2. And voilΓ ! We get the exact same solutions, x=3x=3 and x=βˆ’2x=-2, that we found through factoring. These are two real solutions. The quadratic formula is a universal tool; it guarantees you'll find the solutions, whether they're real, imaginary, distinct, or repeated. It might involve a bit more calculation than factoring, but its reliability is unmatched. It's the safety net that ensures you can always find the answers, no matter how complex the quadratic equation might seem at first glance. Always remember this formula; it's a cornerstone of algebra!

Analyzing the Options: What's the Verdict?

Okay, guys, we've done the detective work! We've used the discriminant, simplified the equation, and even solved it using two different methods (factoring and the quadratic formula). Now, let's circle back to the original question and the multiple-choice options presented: 2x2βˆ’2xβˆ’12=02x^2 - 2x - 12 = 0. The options were:

A. 1 real solution B. 2 real solutions C. 2 imaginary solutions D. 1 real solution and 1 imaginary solution

Based on our thorough analysis, we discovered the following:

  1. Discriminant: We calculated the discriminant (Ξ”\Delta) for the original equation 2x2βˆ’2xβˆ’12=02x^2 - 2x - 12 = 0 (with a=2,b=βˆ’2,c=βˆ’12a=2, b=-2, c=-12) as Ξ”=(βˆ’2)2βˆ’4(2)(βˆ’12)=4+96=100\Delta = (-2)^2 - 4(2)(-12) = 4 + 96 = 100. Since 100>0100 > 0, this immediately tells us that there are two distinct real solutions.
  2. Factoring: By simplifying the equation to x2βˆ’xβˆ’6=0x^2 - x - 6 = 0 and factoring, we found the solutions x=βˆ’2x = -2 and x=3x = 3. These are clearly two real numbers.
  3. Quadratic Formula: Applying the quadratic formula to the simplified equation yielded the same solutions, x=3x = 3 and x=βˆ’2x = -2, further confirming two real solutions.

Given these results, it's crystal clear that our equation possesses two real solutions. Therefore, the correct option among A, B, C, and D is B. 2 real solutions. It's awesome when different methods all point to the same conclusion, right? It gives you that extra confidence that you've nailed the problem. So, remember, whether you use the discriminant as a quick check or go through the full solving process, the goal is to accurately identify the nature and quantity of the solutions. In this case, we've got a pair of solid, real answers waiting for you!

Conclusion: Mastering Quadratic Equations

So there you have it, legends! We've successfully tackled the quadratic equation 2x2βˆ’2xβˆ’12=02x^2 - 2x - 12 = 0 and determined the number and type of solutions. Through the power of the discriminant, simplification, factoring, and the trusty quadratic formula, we consistently arrived at the same answer: two real solutions. This journey highlights the beauty and consistency of mathematics. Each method, while different in approach, leads us to the same truth. Understanding these tools – the discriminant for classification and formulas/factoring for finding the exact values – is fundamental to mastering algebra. Never shy away from simplifying equations; it's a smart move that makes complex problems more approachable. And always remember the quadratic formula; it's your universal key when other methods falter. Keep practicing, keep exploring, and remember that every equation you solve is a step towards greater mathematical confidence. You guys are crushing it! Keep up the amazing work, and I'll catch you in the next math adventure!