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

00:08 Let's find X.
00:12 We'll use the multiplication formulas to expand the parentheses.
00:16 Carefully open the parentheses. Multiply each term with every other term.
00:32 Now let's solve the multiplication and square any terms where needed.
00:40 Simplify by combining like terms.
00:46 Next, let's isolate the variable X.
01:10 And there you have it, that's the solution to our problem!

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