Question

Solve for x, where x > 0 and 84x(x + 2) = 90-13x. Express your answer as a simplified common fraction.

Answer 1

84x(x+2) = 84x² + 168x

84x² + 168x = 90 - 13x

84x² +181x - 90 = 0

bhaskara formula

$\frac{-181+-\sqrt{181^{2}- 4.84.(-90) } }{168 } }$

$\frac{-181+-\sqrt{32.761 +30.240} }{168}$

$\frac{-181+-251}{168}$

since its a positive number, we can't use the minus

so, $\frac{70}{168}$

they're both dividable by 14, so

x = $\frac{5}{12}$ is your answer

hope it helps :)