Question

Solve the following equation for x and give, in the following case, your answer correct to 2 decimal places:

4x² – 5x – 3 = 0

Answer 1

Given equation 4x² – 5x – 3 = 0

Comparing with ax² + bx + c = 0, we have

a = 4, b = – 5, c = – 3

∴ `x = (-b ± sqrt(b^2 - 4ac))/(2a)`

= `(-(-5) ± sqrt((-5)^2 - 4 xx 4 xx (-3)))/(2 xx 4)`

= `(5 ± sqrt(25 + 48))/(8)`

= `(5 ± sqrt(73))/(8)`

= `(5 ± 8.544)/(8)`

= `(5 + 8.544)/(8) or (5 - 8.544)/(8)`

= `(13.544)/(8) or (-3.544)/(8)`

= 1.693 or – 0.443

= 1.69 or – 0.44   ...(correct to 2 decimal places)