Question

谁来帮我解答初三数学题的啊啊

5x(2x+3)=(2x+3)
(x+2)(x-1)=18
(x+3)^2=(2x-1)^2
(x=10)(600-10x)=10000
(x+2)^2+x^2=20
第四题应该是 （x+10)(600-10x)=10000

Answer 1

1. 5x(2x+3)-(2x+3)=(5x-1)(2x+3)=0 x=-3/2,1/5
2. x^2+x-2-18=(x-4)(x+5)=0 x=4,-5
3. (x+3)^2-(2x-1)^2=(x+3+2x-1)(x+3-2x+1)=(3x+2)(-x+4)=0 x=-2/3,4
4. 600x-10x^2+6000-100x-10000=0 -10x^2+500x-4000=0 x^2-50x+400=0 (x-40)(x-10)=0 x=40或10
5. x^2+4x+4+x^2-20=2x^2+4x-16=(2x+8)(x-2)=0 x=-4,2

Answer 2

1. 5x(2x+3)-(2x+3)=(5x-1)(2x+3)=0 x=-3/2,1/5
2. x^2+x-2-18=(x-4)(x+5)=0 x=4,-5
3. (x+3)^2-(2x-1)^2=(x+3+2x-1)(x+3-2x+1)=(3x+2)(-x+4)=0 x=-2/3,4
4. 题目有误
5. x^2+4x+4+x^2-20=2x^2+4x-16=(2x+8)(x-2)=0 x=-4,2

Answer 3

-3/2；1/5
4；-5
-2/3；4
第四题估计是(x+10)(600-10x)=10000 则 答案为 10；40
-4；2

Answer 4

解：(1)5x(2x+3)=(2x+3)
（2x+3）（5x-1)=0 x1=-3/2 x2=1/5
(2)(x+2)(x-1)=18
x^2+x-20=0 (x-4)(x+5)=0 x1=4 x2=-5
(3)(x+3)^2=(2x-1)^2
(x+3-2x+1)(x+3+2x-1)=0 x1=4 x2=-2/3
(4)(x+10)(600-10x)=10000
x^2-50x+400=0
(x-40)(x-10)=0 x1=40 x2=10
(5)( x+2)^2+x^2=20
x^2+2x-8=0 (x+4)(x-2)=0 x1=2 x2=-4