数学化简3x-x^2/5x+4 x 18/4x-12

题目

数学化简3x-x^2/5x+4 x 18/4x-12
(3x-x^2)/(5x+4) x 18/(4x-12)

答案

(3x-x²)/(5x+4) × 18/(4x-12)
= [-x(x-3)]/(5x+4) × 18/[4(x-3)]
= [-18x(x-3)]/[4(5x+4)(x-3)]
= -9x/[2(5x+4)]
= -9x/(10x+8)