Solve the Quadratic Equation: x²-8x+16=0 Using Perfect Square Method

Question

x28x+16=0 x^2-8x+16=0

Video Solution

Solution Steps

00:00 Find X
00:03 Convert 16 to 4 squared
00:14 Factor into components
00:20 Use shortened multiplication formulas to find the product
00:24 Find what makes the brackets equal zero
00:30 And this is the solution to the question

Step-by-Step Solution

Let's solve the given equation:

x28x+16=0 x^2-8x+16=0 We identify that we can factor the expression on the left side using the perfect square trinomial formula:

(a±b)2=a2±2ab+b2 (a\pm b)^2=a^2\pm2ab+b^2 Let's do this:

x28x+16=0x28x+42=0x22x4+42=0(x4)2=0 x^2-8x+16=0 \\ x^2\textcolor{blue}{-8x}+4^2=0 \\ x^2\textcolor{blue}{-2\cdot x\cdot4}+4^2=0 \\ \downarrow\\ (x-4)^2=0 Note that factoring using this formula was only possible because the middle term in the expression (which is in first power in this case and highlighted in blue in the previous calculation) indeed matched the middle term in the perfect square trinomial formula,

We'll continue and solve the resulting equation by taking the square root of both sides:

(x4)2=0/x4=0x=4 (x-4)^2=0 \hspace{6pt}\text{/}\sqrt{\hspace{4pt}}\\ x-4=0\\ \boxed{x=4} Therefore, the correct answer is answer C.

Answer

x=4 x=4