计算。7道题
(1).(x+a)(x+b);2).(2x-y)(2x+3y);3),(3x^2y-2x^3)÷(-2x)^2;4).(2/1)^0×3^-2.5).x^2·x^3+x^...
(1). (x+a)(x+b); 2). (2x-y)(2x+3y); 3),(3x^2y-2x^3)÷(-2x)^2;
4) . (2/1)^0×3^-2. 5). x^2·x^3+x^7÷x^2
6).(x+5)(x-5)-(x+1)(x+5) 7)[(x-y)^2+(x+y)(x-y)]÷2X 展开
4) . (2/1)^0×3^-2. 5). x^2·x^3+x^7÷x^2
6).(x+5)(x-5)-(x+1)(x+5) 7)[(x-y)^2+(x+y)(x-y)]÷2X 展开
展开全部
(1). (x+a)(x+b)=x^2+ax+bx+ab
( 2). (2x-y)(2x+3y)=4x^2+4xy-3y^2
(3),(3x^2y-2x^3)÷(-2x)^2=3/4y-1/2x
(4) .(2/1)^0×3^-2.=1*1/9=1/首厅9
( 5). x^2·x^3+x^7÷x^2=2x^5
(者锋隐6).(x+5)(x-5)-(x+1)(x+5) =x^2-25-x^2-6x-5=-6x-30
(7)[(x-y)^2+(x+y)(x-y)]÷2X=[x^2-2xy+y^2+x^2-y^2]/2x=[2x^2-2xy]/基洞2x=x-y
( 2). (2x-y)(2x+3y)=4x^2+4xy-3y^2
(3),(3x^2y-2x^3)÷(-2x)^2=3/4y-1/2x
(4) .(2/1)^0×3^-2.=1*1/9=1/首厅9
( 5). x^2·x^3+x^7÷x^2=2x^5
(者锋隐6).(x+5)(x-5)-(x+1)(x+5) =x^2-25-x^2-6x-5=-6x-30
(7)[(x-y)^2+(x+y)(x-y)]÷2X=[x^2-2xy+y^2+x^2-y^2]/2x=[2x^2-2xy]/基洞2x=x-y
追问
有过程吗?
追答
(1). (x+a)(x+b)=x^2+ax+bx+ab 十字相乘法
( 2). (2x-y)(2x+3y)=4x^2+4xy-3y^2 十字相乘法
(3),(3x^2y-2x^3)÷(-2x)^2=(3x^2y-2x^3)/(4x^2)=3/4y-1/2x
(4) .(2/1)^0×3^-2.=1*1/9=1/9
( 5). x^2·x^3+x^7÷x^2=x^(2+3)+x^(7-2)=x^5+x^5=2x^5
(6).(x+5)(x-5)-(x+1)(x+5) =x^2-25-x^2-6x-5=-6x-30 平方差公式、十字相乘法
(7)[(x-y)^2+(x+y)(x-y)]÷2X=[x^2-2xy+y^2+x^2-y^2]/2x=[2x^2-2xy]/2x=x
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