Question

Solve the following equation by using formula :

x² + 7x – 7 = 0

Answer 1

x² + 7x – 7 = 0
Here a = 1, b = 7, c = -7
∴ D = b² - 4ac
= (7)² - 4 x 1(-7)
= 49 + 28
= 77

∵ x = `(-b ± sqrt("D"))/(2a)`

= `(-7 ± sqrt(77))/(2 xx 1)`

= `(-7 ± sqrt(77))/(2)`

∴ `x_1 = (-7 + sqrt(77))/(2) and x_2 = (-7 - sqrt(77))/(2)`

Hence x = `(-7 + sqrt(77))/(2), (-7 - sqrt(77))/(2)`.