已知2a^3+16b^3=8,a+2b=3,求多项式1/3(a^2)-2/3(ab)+4/3(b^2)
会的帮一下忙,先谢谢了
参考答案:2a^3+16b^3=8,a+2b=3
a^3+8b^3=4
[a+2b][a^2+4b^2-2ab]=4
a^2+4b^2-2ab=4/3
1/3(a^2)-2/3(ab)+4/3(b^2)
=1/3[a^2+4b^2-2ab]
=1/3*4/3
=4/9
会的帮一下忙,先谢谢了
参考答案:2a^3+16b^3=8,a+2b=3
a^3+8b^3=4
[a+2b][a^2+4b^2-2ab]=4
a^2+4b^2-2ab=4/3
1/3(a^2)-2/3(ab)+4/3(b^2)
=1/3[a^2+4b^2-2ab]
=1/3*4/3
=4/9