Question

9y²+21-18=0
pls tell how to do​

Answer 1

Hello,

I think it is 9y² + 21y - 18 = 0

we have a = 9 ; b = 21 and c = -18

∆ = b² - 4ac = 21² - 4 × 9 × (-18) = 1089 > 0

x1 = (-b - √∆)/2a = (-21 - 33)/9 = 6

x2 = (-b + √∆)/2a = (-21 + 33)/9 = 12/9 = 4/3

S = {4/3 ; 6}