Question

解方程（30－2x）（24－2x）x＝1040

Answer 1

(30 - 2x) (24 - 2x) x = 1040

(720 - 60 x - 48 x + 4 x^2) x = 1040

(4 x^2 - 108x + 720) x = 1040

4 x^3 - 108x^2 + 720 x - 1040 = 0

x^3 - 27 x^2 + 108 x - 260 =0

(x - 2) (x^2 - 25 x + 130) = 0

(x - 2 = 0) 或 (x^2 - 25 x + 130 = 0)

(x = 2) 或 x={-(-25)-[(-25)^2-4(1)(130)]^(-1/2)}/(2*1)

或 x={-(-25)-[(-25)^2-4(1)(130)]}/(2*1)

(x = 2) 或 {x = [25 - (105)^(-1/2)]/2 }

或 {x = [25 + (105)^(-1/2)]/2 }