Solve for X: Perfect Square (x-4)² Equals Product (x+2)(x-1)

Question

Solve for x:

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

Video Solution

Solution Steps

00:00 Find X
00:04 Use the abbreviated multiplication formulas to open the parentheses
00:08 Open parentheses properly, multiply each factor by each factor
00:24 Solve the multiplication and square
00:32 Simplify what we can
00:38 Isolate X
01:02 And this is the solution to the question

Step-by-Step Solution

Let's solve the equation, first we'll simplify the algebraic expressions using the extended distribution law:

(a+b)(c+d)=ac+ad+bc+bd (a+b)(c+d)=ac+ad+bc+bd We'll use the shortened multiplication formula for a squared binomial:

(a±b)2=a2±2ab+b2 (a\pm b)^2=a^2\pm2ab+b^2 We'll therefore apply the law and formula mentioned and open the parentheses in the expressions in the equation:

(x4)2=(x+2)(x1)x22x4+42=x2x+2x2x28x+16=x2+x2 (x-4)^2=(x+2)(x-1) \\ x^2-2\cdot x\cdot4+4^2=x^2-x+2x-2 \\ x^2-8x+16=x^2+x-2 We'll continue and combine like terms, by moving terms between sides - we can notice that the squared term cancels out and therefore it's a first-degree equation, which we'll solve by isolating the variable term on one side and dividing both sides of the equation by its coefficient:

x28x+16=x2+x29x=18/:(9)x=2 x^2-8x+16=x^2+x-2\\ -9x=-18\hspace{8pt}\text{/}:(-9)\\ \boxed{x=2} Therefore the correct answer is answer A.

Answer

x=2 x=2