4(x-2)(x+5)-(2x-3)(2x+1)=54(x的平方+5x-2x-10)-(4x的平方+2x-6x-3)=54x的平方+20x-8x-40-4x的平方-2x+6x+3=54x的平方-4x的平方+20x-8x-2x+6x=5+40-3 16x=42 x=2.625=21/8 给赏啊,拜托了啦
4(x-2)(x+5)-(2x-3)(2x+1)=54(x^2+3x-10)-(4x^2-4x-3)=54x^2+12x-40-4x^2+4x+3=516x=5+40-316x=42x=21/8
4(x-2)(x+5)-(2x-3)(2x+1)=5
4x^2+20x-8x-40-4x^2-2x+6x+3=5
16x=42
x=42/16
x=21/8