Question

Solve the following equation: `x - (18)/x = 6`. Give your answer correct to two x significant figures.

Answer 1

`x - (18)/x = 6`
⇒ x² – 6x – 18 = 0
a = 1, b = -6, c = -18

 x = `(-b ± sqrt(b^2 - 4ac))/(2a)`

= `(6 ± sqrt(36 + 72))/(2)`

= `(6 ± sqrt(108))/(2)`

= `(6 ± 6sqrt(3))/(2)` or `(6(1 - 1.73))/(2)`
= 3 x 2.73 or 3 x -0.73
= 8.19 or -2.19.