Question

（30+2X）x（50-X）=2100一元二次方程

步骤

Answer 1

【参考答案】

原方程即
1500-30x+100x-2x^2-2100=0
-2x^2 +70x-600=0
x^2 -35x+300=0
(x-15)(x-20)=0
解得 x=20或15

Answer 2

（30+2X)(50-X)=2100
1500-30X+100X-2X^2=2100
X^2-35X+300=0
(X-15)(X-20)=0
解得：X1=15 X2=20

Answer 3

（30+2X）x（50-X）=2100
1500-30x+100x-2x^2=2100
2x^2-70x+600=0
x^2-35x+300=0
(x-15)(x-20)=0
x1=15
x2=20

Answer 4

两边除以-2
(x+15)(x-50)=-1050
x^2-35x-750+1050=0
x^2-35x+300=0
(x-15)(x-20)=0
x=15,x=20

Answer 5

（30+2X）x（50-X）-2100=0
-2 (300 - 35 X + X^2)=0
-2(X - 15)(X - 20)=0
X = 15, X = 20