Question

Solve the following quadratic equation by using formula method :

7y² - 5y - 2 = 0

Answer 1

7y² - 5y - 2 = 0

Comparing with ax² + bx + c = 0

a = 7, b = -5 and c = -2

b² - 4ac = (-5)2 - 4(7) (-2)

= 25 + 56

= 81

By formula method

Y = `(-"b" ± sqrt(b^2 - 4"ac"))/"2a"` 

= `(5 ± sqrt81)/"2(7)"`

= `(5 ± 9)/14`

Y = `(5 + 9)/14` Or Y = `(5 - 9)/14`

Y = `14/14` Or Y = `4/14`

Y = 1 Or Y = `(-2)/7`