Solve (x-4)² = (x+2)(x-1): Comparing Squared and Factored Forms

Question

(x4)2=(x+2)(x1) (x-4)^2=(x+2)(x-1)

Video Solution

Solution Steps

00:00 Solve
00:03 We'll use shortened multiplication formulas to open the parentheses
00:09 Open parentheses properly, multiply each factor by each factor
00:21 Calculate the multiplications
00:27 Collect like terms
00:32 Simplify what we can
00:44 Isolate X
01:11 And this is the solution to the question

Step-by-Step Solution

Let's examine the given equation:

(x4)2=(x+2)(x1) (x-4)^2=(x+2)(x-1) First, let's simplify the equation, using the perfect square binomial formula:

(a±b)2=a2±2ab+b2 (a\pm b)^2=a^2\pm2ab+b^2 and the expanded distributive law,

We'll start by opening the parentheses using the perfect square binomial formula mentioned and using the expanded distributive law and then we'll move terms and combine like terms:

(x4)2=(x+2)(x1)x22x4+42=x2x+2x2x28x+16=x2x+2x2x28x+16x2+x2x+2=09x+18=0 (x-4)^2=(x+2)(x-1) \\ \downarrow\\ x^2-2\cdot x\cdot4+4^2=x^2-x+2x-2\\ x^2-8x+16=x^2-x+2x-2\\ x^2-8x+16-x^2+x-2x+2=0\\ -9x+18=0 We got a first-degree equation, we'll solve it in the regular way by isolating the variable on one side:

9x+18=09x=18/:(9)x=2 -9x+18=0 \\ -9x=-18\hspace{6pt}\text{/}:(-9)\\ \boxed{x=2}

Let's summarize the equation solving steps:

(x4)2=(x+2)(x1)x28x+16=x2x+2x29x+18=0x=2 (x-4)^2=(x+2)(x-1) \\ \downarrow\\ x^2-8x+16=x^2-x+2x-2\\ -9x+18=0 \\ \downarrow\\ \boxed{x=2} Therefore, the correct answer is answer C.

Answer

x=2 x=2