1)
\(\left(a+2b\right)^2+\left(b-a\right)^2-\left(a-b\right)^2\)
\(=\left(a^2+2a.2b+\left(2b\right)^2\right)+\left(b^2-2ba+a^2\right)-\left(a^2-2ab+b^2\right)\)
\(=a^2+4ab+4b^2+b^2-2ab+a^2-a^2+2ab-b^2\)
\(=a^2+4ab+4b^2\)
Rút gọn
1. a, \(\left(a-b\right)^2-\left(a+b\right)^2\)
b,\(\left(a+2b\right)^2+\left(b-a\right)^2-\left(a-b\right)^2\)
2.CMR. \(\left(a-b\right)^2=\left(b-a\right)^2\)
3.Tính \(\left(a-b\right)^4\)
Rút gọn :
\(a,A=\left(3+1\right)\left(3^2+1\right)\left(3^4+1\right)...\left(3^{64}+1\right)\\ b,B=-1^2+2^2-3^2+4^2-...-99^2+100^2\\ c,C=-1^2+2^2-3^2+4^2-...+\left(-1\right)^n\cdot n^2\\ d,D=3\cdot\left(2^2+1\right)\left(2^4+1\right)...\left(2^{64}+1\right)+1\\ e,E=\left(a+b+c\right)^2+\left(a+b-c\right)^2-2\left(a+b\right)^2\\ g,G=\left(a+b+c+d\right)^2+\left(a+b-c-d\right)^2+\left(a+c-b-d\right)^2+\left(a+d-b-c\right)^2\\ h,H=\left(a+b+c\right)^3-\left(b+c-a\right)^3-\left(a+c-b\right)^3+\left(a+b-c\right)^3\\ i,I=\left(a+b\right)^3+\left(b+c\right)^3+\left(c+a\right)^3-3\left(a+b\right)\left(c+b\right)\left(c+a\right)\)
Mọi người ơi, giúp mk vs, đc câu nào hay câu ấy ! Help me!!!!!!!!!!!!!!!!!!
Rút gọn biểu thức: \(A=\dfrac{2}{a-b}+\dfrac{2}{b-c}+\dfrac{2}{c-a}+\dfrac{\left(a-b\right)^2+\left(b-c\right)^2+\left(c-a\right)^2}{\left(a-b\right).\left(b-c\right).\left(c-a\right)}\)
Cho a,b,c là các số thực dương. CMR
\(\frac{2\left(b+c-a\right)^2}{2a^2+\left(b+c\right)^2}+\frac{2\left(c+a-b\right)^2}{2b^2+\left(c+a\right)^2}+\frac{2\left(a+b-c\right)^2}{2c^2+\left(a+b\right)^2}\) ≥ 1
7 Chứng minh các đẳng thức sau
a) \(a^2+b^2=\left(a+b\right)^2-2ab\) ; b) \(a^4+b^4=\left(a^2+b^2\right)^2-2a^2b^2\)
c) \(a^6+b^6=\left(a^2+b^2\right)\left[\left(a^2+b^2\right)^2-3a^2b^2\right]\)
d) \(a^6-b^6=\left(a^2-b^2\right)\left[\left(a^2+b^2\right)^2-a^2b^2\right]\)
Cho a+b+c=abc CMR:
\(a\left(b^2-1\right)\left(c^2-1\right)+b\left(a^2-1\right)\left(c^2-1\right)+c\left(a^2-1\right)\left(b^2-1\right)=4abc\)
Cho a,b,c là các số thực dương. CMR:
\(\frac{2\left(b+c-a\right)^2}{2a^2+\left(b+c\right)^2a+^{ }}+\frac{2\left(c+a-b\right)}{2b^2+\left(c+a\right)^2}+\frac{2\left(a+b-c\right)^2}{2c^2+\left(a+b\right)^2}\)\(\ge1\)
Dùng Bunhiacopxki dạng phân thức
1/rút gọn biểu thức:
\(A=\frac{2}{a-b}+\frac{2}{b-c}+\frac{2}{c-a}+\frac{\left(a-b\right)^2+\left(b-c\right)^2+\left(c-a\right)^2}{\left(a-b\right)\left(b-c\right)\left(c-a\right)}\)
Cho a,b,c > 0. CMR P = \(\frac{a^2}{b\left(b+2c\right)}+\frac{b^2}{c\left(c+2a\right)}+\frac{c^2}{a\left(a+2b\right)}\) ≥ 1
