Question

Solve the equation 5x² – 3x – 4 = 0 and give your answer correct to 3 significant figures:

Answer 1

We have 5x² – 3x – 4 = 0
Here a = 5, b = – 3, c = – 4

x = `(-b ± sqrt(b^2 - 4ac))/(2a)`

= `(3 ± sqrt(9 + 4 xx 5 xx 4))/(2 xx 5)`

= `(3 ± sqrt(89))/(10)`

`x = (3 + 9.43)/(10) or x = (3 - 9.43)/(10)`

⇒ `x = (12.43)/(10) or x = (-6.43)/(10)`
⇒ x = 1.24 or x = -0.643.