Question

Solve the following quadratic equation: x² + 4x − 8 = 0

Give your answer correct to one decimal place.

Answer 1

Given:

x² + 4x − 8 = 0

`x = [-b ± sqrt(b^2 − 4ac)]/(2a)`

with a = 1, b = 4, c = −8

`x = [-4 ± sqrt(16 − 4(1)(-8))]/2`

`= [-4 ± sqrt(48)]/2`

`= -2 ± 2`√3`

Numeric values: x = 1.4641

 and x = −5.4641

so to one decimal place:

x = 1.5 and x = −5.5