Đáp án:
c.$-\dfrac{8a^6b^6}{125}+\dfrac{12a^4b^6c}{25}-\dfrac{6a^2b^6c^2}{5}+b^6c^3$
d.$\dfrac{8c^3}{d^6}+\dfrac{48c}{d^5}+\dfrac{96}{cd^4}+\dfrac{64}{c^3d^3}$
Giải thích các bước giải:
c.Ta có:
$(-\dfrac25a^2b^2+b^2c)^3$
$=(-\dfrac25a^2b^2)^3+3\cdot (-\dfrac25a^2b^2)^2\cdot b^2c+3\cdot (-\dfrac25a^2b^2)\cdot (b^2c)^2+(b^2c)^3$
$=-\dfrac{8a^6b^6}{125}+\dfrac{12a^4b^6c}{25}-\dfrac{6a^2b^6c^2}{5}+b^6c^3$
d.Ta có:
$(\dfrac{2c}{d^2}+\dfrac{4}{cd})^3$
$=\left(\dfrac{2c}{d^2}\right)^3+3\left(\dfrac{2c}{d^2}\right)^2\dfrac{4}{cd}+3\cdot \dfrac{2c}{d^2}\left(\dfrac{4}{cd}\right)^2+\left(\dfrac{4}{cd}\right)^3$
$=\dfrac{8c^3}{d^6}+\dfrac{48c}{d^5}+\dfrac{96}{cd^4}+\dfrac{64}{c^3d^3}$
