x^2 - 4x = 80
x^2 - 4x + 4 = 80 + 4 (Divide b, which is 4, by 2 and square it.)
x^2 - 4x + 4 = 84
sqrt(x + 2)^2 = sqrt(84)
x + 2 = plus or minus sqrt(84)
Subtract 2 from both sides
x = -2 plus or minus sqrt(84)
Answer:
A value that satisfies this equation is called a root, zero or solution of the equation!! We have three ... Solve each by factoring. 1) x2 + 4x -5 = 0 ... Follow the explanation and sample problem to review completing the square.
Explanation:
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