9x ²+42x+49 25x ²-2xy+1/25y ² 27+(x-3)(x ²+3x+9) x ³+3x ²+3x+1 20/08/2021 Bởi Kaylee 9x ²+42x+49 25x ²-2xy+1/25y ² 27+(x-3)(x ²+3x+9) x ³+3x ²+3x+1
Đáp án: $9x^2 +42x +49$ $ = (3x)^2 + 2 . 3 . 7 + 7^2 $ $ = (3x +7)^2$ $25x^2 -2xy +\dfrac{1}{25}y^2$ $ = (5x)^2 – 2 . 5x . \dfrac{1}{5}y +\dfrac{1}{25}y^2$ $ = (5x – \dfrac{1}{5}y)^2$ $27 + (x-3)(x^2+3x+9)$ $ = 27+x³-27$ $ =x³$ $x^3 +3x^2 +3x +1$ $ = x^3 +3.x^2.1 + 3.x.1^2 + 1^3$ $ = (x+1)³$ Bình luận
`9x^2+ 42x+49` `(3x)^2+2.3x.7+7^2` `=(3x+7)^2` `25x^2- 2xy+1/25 y^2` `(5x)^2-2.5x. 1/5 y+ (1/5 y)^2` `=(5x- 1/5 y)^2` `27+(x-3)(x^2+3x+9)` `27+(x-3)(x^2+ 3x+ 3^2)` `=27+x^3- 27` `=x^3` `x^3+ 3x^2+ 3x+1` `x^3+ 3x^2 .1+3x.1^2+ 1^3` `=(x+1)^3` chúc học tốt Bình luận
Đáp án:
$9x^2 +42x +49$
$ = (3x)^2 + 2 . 3 . 7 + 7^2 $
$ = (3x +7)^2$
$25x^2 -2xy +\dfrac{1}{25}y^2$
$ = (5x)^2 – 2 . 5x . \dfrac{1}{5}y +\dfrac{1}{25}y^2$
$ = (5x – \dfrac{1}{5}y)^2$
$27 + (x-3)(x^2+3x+9)$
$ = 27+x³-27$
$ =x³$
$x^3 +3x^2 +3x +1$
$ = x^3 +3.x^2.1 + 3.x.1^2 + 1^3$
$ = (x+1)³$
`9x^2+ 42x+49`
`(3x)^2+2.3x.7+7^2`
`=(3x+7)^2`
`25x^2- 2xy+1/25 y^2`
`(5x)^2-2.5x. 1/5 y+ (1/5 y)^2`
`=(5x- 1/5 y)^2`
`27+(x-3)(x^2+3x+9)`
`27+(x-3)(x^2+ 3x+ 3^2)`
`=27+x^3- 27`
`=x^3`
`x^3+ 3x^2+ 3x+1`
`x^3+ 3x^2 .1+3x.1^2+ 1^3`
`=(x+1)^3`
chúc học tốt