Solve x^2- 8x = 20 by completing the square. Which is the solution set of the equation? (-2,-10) {2, 10) {-2, 10) {2,-10)
Mathematics · College · Tue Nov 03 2020
llm
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We have ,
x² - 8x = 20
Or, x² -8x - 20 =0
(x)² - 2(x)(4) + (4)² -36 =0 {16 - 36 = -20}
{By (a-b)² = a² -2ab + b²}
(x - 4)² - 36 =0
(x - 4)² = 36
Taking square root of both sides, we get
x- 4 = ±6
x = ±6 + 4
Taking positive sign
x = 6 + 4 = 10
Taking negative sign
x = -6 + 4 = -2
Thus, solutions are (-2,10).