a: \(\left(a+b\right)^3-3ab\left(a+b\right)\)
\(=\left(a+b\right)\left(a^2+2ab+b^2-3ab\right)\)
\(=\left(a+b\right)\left(a^2-ab+b^2\right)\)
\(=a^3+b^3\)
b: \(\left(a-b\right)^3+3ab\left(a-b\right)\)
\(=\left(a-b\right)\left(a^2-2ab+b^2+3ab\right)\)
\(=\left(a-b\right)\left(a^2+ab+b^2\right)\)
\(=a^3-b^3\)
Chứng minh:
a) \(\left(a^3+b^3\right)=\left(a+b\right)^3-3ab\left(a+b\right)\)
b) \(\left(a^3-b^3\right)=\left(a-b\right)^3+3ab\left(a-b\right)\)
Áp dụng tính \(a^3+b^3\) biết \(ab=6\) và \(a+b=-5\)
Chứng minh rằng:
a)\(a^3+b^3=\left(a+b\right)^3-3ab\left(a+b\right)\)
b)\(\left(a-b\right)^3+3ab\left(a-b\right)=a^3-b^3\)
c)\(\left(a+b\right)^2-\left(a-b\right)^2=4ab\)
Chứng minh
\(a^3+b^3=\left(a+b\right)^3-3ab\left(a+b\right)\)
\(\left(a+b+c\right)^3=a^3+b^3+c^3+3\left(a+b\right)\left(b+c\right)\left(c+a\right)\)
chung minh
\(a^3+b^3=\left(a+b\right)^3-3ab\left(a+b\right)\)
\(a^3-b^3=\left(a-b\right)^3+3ab\left(a-b\right)\)
Chứng minh
\(^{a^3+b^3=\left(a+b\right)^3-3ab\left(a+b\right)}\)
chứng minh
\(a^3-b^3=\left(a-b\right)^3+3ab\left(a-b\right)\)
CMR
a) \(a^3+b^3=\left(a+b\right)^3-3ab\left(a+b\right)\)
b)\(a^3-b^3=\left(a-b\right)^3+3ab\left(a-b\right)\)
Giúp mk vs mk đg cần gấp
Tính \(M=a^3+b^3+3ab\left(a^2+b^2\right)+6a^2b^2\left(a+b\right)\) biết a+b=1
Chứng minh
\(\left(a+b\right)^3=\left(a-b\right)\left(a^2+ab+b^2\right)-3ab\left(a-b\right)\)
C/minh: \(\left(a+b\right)^3=a^3+b^3+3ab\left(a+b\right)\)
