Question

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

O {4 - V19, 4 + V19}
O {4 - V11, 4 + V11}
O {4 - V8,4 + V8}
O {4 - V3, 4 + V3}

Answer 1

first option

Explanation:

x² - 8x = 3

to complete the square

add ( half the coefficient of the x- term )² to both sides

x² + 2(- 4)x + 16 = 3 + 16

(x - 4)² = 19 ( take square root of both sides )

x - 4 = ±
`√(19)` ( add 4 to both sides )

x = 4 ±
`√(19)`

then

x = 4 -
`√(19)` , x = 4 +
`√(19)`