Question

Solve x2 – 8x = 3 by completing the square. Which is the solution set of the equation?

(4 minus StartRoot 19 EndRoot comma 4 + StartRoot 19 EndRoot)
(4 minus StartRoot 11 EndRoot comma 4 + StartRoot 11 EndRoot)
(4 minus StartRoot 8 EndRoot comma 4 + StartRoot 8 EndRoot)
(4 minus StartRoot 3 EndRoot comma 4 + StartRoot 3 EndRoot)

Answer 1

x^2 − 8x = 3
Complete the square: x^2 − 8x + 16 = 3 + 16 ⇒ (x − 4)^2 = 19
So x − 4 = ±√19 ⇒ x = 4 ± √19.

Solution set: (4 − √19, 4 + √19).