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

00:06 Let's find the value of X.
00:09 First, change 16 to 4 squared.
00:20 Next, break it down into smaller parts.
00:26 Now, use quick multiplication tricks to get the product.
00:31 Look for numbers that make each section equal zero.
00:36 And that's how we solve this 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