1/ x (x ² – y) – x ²(x+y) + y(x ² – x ) tại x=1/2 y= -100 2/(x – 5)(2x+3) – 2x(x-3) + x + 7 22/08/2021 Bởi Reagan 1/ x (x ² – y) – x ²(x+y) + y(x ² – x ) tại x=1/2 y= -100 2/(x – 5)(2x+3) – 2x(x-3) + x + 7
Đáp án: Giải thích các bước giải: $1) x(x^2-y)-x^2(x+y)+y(x^2-x)$ $=x^3-xy-x^3-x^2y+x^2y-xy$ $=(x^3-x^3)-(xy-xy)-(x^2y-x^2y)$ $=0$ $2) (x-5)(2x+3)-2x(x-3)+x+7$ $=x(2x+3)-5(2x+3)-2x^2+6x+x+7$ $=2x^2+3x-10x-15-2x^2+7x+7$ $=(2x^2-2x^2)+(3x-10x+7x)-(15-7)$ $=-8$ Bình luận
`x (x ^2 – y) – x ^2(x+y) + y(x ^2 – x )` `=x^3-xy-x^3-x^2y+x^2y+xy` `=(x^3-x^3)+(-x^2y+x^2y)+(-xy+xy)` `=0` `(x – 5)(2x+3) – 2x(x-3) + x + 7` `=2x^2+3x-10x-15-2x^2+6x+x+7` `=(2x^2-2x^2)+(3x-10x+6x+x)+(-15+7)` `=-8` Bình luận
Đáp án:
Giải thích các bước giải:
$1) x(x^2-y)-x^2(x+y)+y(x^2-x)$
$=x^3-xy-x^3-x^2y+x^2y-xy$
$=(x^3-x^3)-(xy-xy)-(x^2y-x^2y)$
$=0$
$2) (x-5)(2x+3)-2x(x-3)+x+7$
$=x(2x+3)-5(2x+3)-2x^2+6x+x+7$
$=2x^2+3x-10x-15-2x^2+7x+7$
$=(2x^2-2x^2)+(3x-10x+7x)-(15-7)$
$=-8$
`x (x ^2 – y) – x ^2(x+y) + y(x ^2 – x )`
`=x^3-xy-x^3-x^2y+x^2y+xy`
`=(x^3-x^3)+(-x^2y+x^2y)+(-xy+xy)`
`=0`
`(x – 5)(2x+3) – 2x(x-3) + x + 7`
`=2x^2+3x-10x-15-2x^2+6x+x+7`
`=(2x^2-2x^2)+(3x-10x+6x+x)+(-15+7)`
`=-8`