Question

Solve the following equation by using formula : 

25x² + 30x + 7 = 0

Answer 1

25x² + 30x + 7 = 0
Here a = 25, b = 30, c = 7
D = b² - 4ac
= (30)² - 4 x 25 x 7
= 900 - 700
= 200

∵ x = `(-b ± sqrt("D"))/(2a)`

= `(-30 ± sqrt(200))/(2 xx 25)`

= `(-30 ±sqrt(100 xx 2))/(50)`

= `(-30 ± 10sqrt(2))/(50)`

= `(-3 ± sqrt(2))/(5)`

∴ `x_1 = (-3 + sqrt(2))/(5) and x_2 = (-3 - sqrt(2))/(5)`

Hence x = `(-3 + sqrt(2))/(5), (-3 - sqrt(2))/(5)`.