数学计算题、3（x-5)的平方=2(5-x)(2x-1)(x+1)=(3x+1)(x+1)(x-2)(x-5)=70(2x+1)的平方+3(2x+1)+2=0用因式分解法.

Question

数学计算题、
3（x-5)的平方=2(5-x)
(2x-1)(x+1)=(3x+1)(x+1)
(x-2)(x-5)=70
(2x+1)的平方+3(2x+1)+2=0
用因式分解法.

Answer 1

1、3(x-5)²=2(5-x)
3(x-5)²+2(x-5)=0
(3x-15+2)(x-5)=0
(3x-13)(x-5)=0
x=13/3或x=5
2、(2x-1)(x+1)=(3x+1)(x+1)
(2x-1)(x+1)-(3x+1)(x+1)=0
[(2x-1)- (3x+1)] (x+1)=0
(x+2) (x+1)=0
x=-2或x=-1
3、(x-2)(x-5)=70
x²-7x+10-70=0
x²-7x-60=0
(x-12)(x+5)=0
x=12或x=-5
4、(2x+1)²+3(2x+1)+2=0
4x²+4x+1+6x+3+2=0
4x²+10x+6=0
2x²+5x+3=0
(x+1)(2x+3)=0
x=-1或x=-3/2