Cho \(a=-6,b=3,c=-2\).
Tính :
\(\left|a+b-c\right|,\left|a-b+c\right|,\left|a-b-c\right|\)
Cho 3x-y=6 Tính giá trị biểu thức
A= \(\frac{a^3}{\left(a-b\right)\left(a-c\right)}+\frac{b^3}{\left(b-a\right)\left(b-c\right)}+\frac{c^3}{\left(c-a\right)\left(c-b\right)}\)
Cho a,b,c khác 1 và a+b+c=3. Tính\(A=\frac{\left(a-1\right)^2}{\left(b-1\right)\left(c-1\right)}+\frac{\left(b-1\right)^2}{\left(c-1\right)\left(a-1\right)}+\frac{\left(c-1\right)^2}{\left(a-1\right)\left(b-1\right)}\)
Cho a+b+c\(a^3+b^3+c^3=3abc\) áp dụng tính B=\(\frac{\left(a^2-b^2\right)^3+\left(b^2-c^2\right)^3+\left(c^2-a^2\right)^3}{\left(a-b\right)^3+\left(b-c\right)^3+\left(c-a\right)^3}\)
Cho
\(\sqrt{a}+\sqrt{b}+\sqrt{c}=\sqrt{3}\)
\(\sqrt{\left(a+2b\right)\left(a+2c\right)}+\sqrt{\left(b+2a\right)\left(b+2c\right)}+\sqrt{\left(c+2a\right)\left(c+2b\right)}=3\)
Hãy tính \(\left(2\sqrt{a}+3\sqrt{b}-4\sqrt{c}\right)^2\)
PTĐT thành nhân tử
a) \(A=a\left(b+c-a\right)^2+b\left(c+a-b\right)^2+c\left(a+b-c\right)^2+\left(a+b-c\right)\left(b+c-a\right)\left(c+a-b\right)\)
b) \(B=\left(a+b-c\right)^3+\left(a-b+c\right)^3+\left(-a+b+c\right)^3-\left(a+b+c\right)^3\)
c) \(C=bc\left(a+b\right)\left(b-c\right)-ac\left(b+d\right)\left(a-c\right)+ab\left(c+d\right)\left(c-b\right)\)
Cho a + b + c = 6 . Tính giá trị biểu thức :
\(\frac{a^3+b^3+c^3-3ab}{\left(a-b\right)^2+\left(b-c\right)^2+\left(c-a\right)^2}\)
cho \(a+b+c=0\) tính \(\dfrac{a^3+b^3+c^3}{\left(a-b\right)^2+\left(b-c\right)^2+\left(c-a\right)^2}\)
Cho a-b+c=-4. Tính B = \(\dfrac{a^3-b^3+c^3+3abc}{\left(a+b\right)^2+\left(b+c\right)^2+\left(c-a\right)^2}\)
\(B=\dfrac{a^3+c^3+3ac\left(a+c\right)-b^3-3ac\left(a+c\right)+3abc}{\left(a+b\right)^2+\left(b+c\right)^2+\left(c-a\right)^2}\)
\(=\dfrac{\left(a+c\right)^3-b^3-3ac\left(a+c-b\right)}{\left(a+b\right)^2+\left(b+c\right)^2+\left(c-a\right)^2}\)
\(=\dfrac{\left(a+c-b\right)\left[\left(a+c\right)^2+b\left(a+c\right)+b^2\right]-3ac\left(a+c-b\right)}{\left(a+b\right)^2+\left(b+c\right)^2+\left(c-a\right)^2}\)
\(=\dfrac{\left(a+c-b\right)\left(a^2+b^2+c^2+ab+bc-ac\right)}{\left(a+b\right)^2+\left(b+c\right)^2+\left(c-a\right)^2}\)
\(=\dfrac{-2\left(2a^2+2b^2+2c^2+2ab+2bc-2ca\right)}{\left(a+b\right)^2+\left(b+c\right)^2+\left(c-a\right)^2}\)
\(=\dfrac{-2\left[\left(a+b\right)^2+\left(b+c\right)^2+\left(c-a\right)^2\right]}{\left(a+b\right)^2+\left(b+c\right)^2+\left(c-a\right)^2}=-2\)
Bài 1: CMR với mọi số thực a; b; c thì:
\(\left(a+b\right)^6+\left(b+c\right)^6+\left(c+a\right)^6\ge\dfrac{16}{61}\left(a^6+b^6+c^6\right)\)\
Bài 2: Cho a;b;c là các cạnh của tam giác:
CMR: \(a^2b\left(a-b\right)+b^2c\left(b-c\right)+c^2a\left(c-a\right)\ge0\)
Giúp mk với các bạn ơi
1)\(\frac{1}{\left(a-b\right)\left(a-c\right)}+\frac{1}{\left(b-c\right)\left(b-a\right)}+\frac{1}{\left(c-a\right)\left(c-b\right)}\)
2)\(\frac{a^2}{\left(a-b\right)\left(a-c\right)}+\frac{b^2}{\left(b-c\right)\left(b-a\right)}\frac{c^2}{\left(c-a\right)\left(c-b\right)}\)
3)\(\frac{1}{x^2+3x+2}+\frac{2x}{x^3+4x^2+4x}+\frac{1}{x^2+5x+6}\)