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- Nhân cả tử và mẫu phân thức thứ nhất với a
- Nhân cả tử và mẫu phân thức thứ 2 với ac
- Thay abc =2016 ta có mẫu số chung là :
3ac - 4032 +2016a
- Rút gọn => đáp án : -1
\(P=\frac{2bc-2016}{3c-2bc+2016}-\frac{2b}{3-2b+ab}-\frac{4032-3ac}{3ac-4032+2016a}\)
Ta rút gọn từng biểu thức
\(+)\frac{2bc-2016}{3c-2bc+2016}=-1+\frac{3c}{3c-2bc+2016}\)
\(+)\frac{-2b}{3-2b+ab}=\frac{-2bc}{3c-2bc+abc}=\frac{-2bc}{3c-2bc+2016}\)
\(+)\frac{4032-3ac}{3ac-4032+2016a}=-1+\frac{2016a}{3ac-2abc+2016a}\)
\(=-1+\frac{2016}{3c-2bc+2016}\)
\(\Rightarrow P=-1\)
Ta có:
\(+)\frac{2bc-2016}{3c-2bc+2016}=-1+\frac{3c}{3c-2bc+2016}\left(1\right)\)
\(+)\frac{-2b}{3-2b+ab}=\frac{-2bc}{3c-2bc+abc}=\frac{-2bc}{3c-2bc+2016}\left(2\right)\)
\(+)\frac{4032-3ac}{3ac-4032+2016a}=-1+\frac{2016a}{3ac-2abc+2016a}=-1+\frac{2016}{3c-2bc+2016}\left(3\right)\)
\(P=\left(1\right)+\left(2\right)+\left(3\right)=-1\)
Vậy .........
\(P=\dfrac{2bc-2016}{3c-2bc+2016}-\dfrac{2b}{3-2b+ab}+\dfrac{4032-3ac}{3ac-4032+2016c}\)
\(=\dfrac{2bc-abc}{3c-2bc+abc}-\dfrac{2b}{3-2b+ab}+\dfrac{2abc-3ac}{3ac-2abc+a^2bc}\)
\(=\dfrac{2b-ab}{3-2b+ab}-\dfrac{2b}{3-2b+ab}+\dfrac{2b-3}{3-2b+ab}\)
\(=\dfrac{2b-ab-2b+2b-3}{3-2b+ab}\)
\(=\dfrac{-3+2b-ab}{3-2b+ab}=-1\).
a) \(\dfrac{3ac}{a^3b}=\dfrac{3c}{a^2b}\)
\(\dfrac{6c}{2a^2b}=\dfrac{3c}{a^2b}\)
\(\Rightarrow\dfrac{3ac}{a^3b}=\dfrac{6c}{2a^2b}\)
b) \(\dfrac{3ab-3b^2}{6b^2}=\dfrac{3b\left(a-b\right)}{6b^2}=\dfrac{a-b}{2b}\left(dpcm\right)\)
`a, (3ac)/(a^3b) = (3c)/(a^2b)`
`(6c)/(2a^2b) = (3c)/(a^2b)`
Vậy hai phân thức `=` nhau
`b, (3ab-3b^2)/(6b^2) = (3b(a-b))/(6b^2) = (a-b)/(2b)`
Vậy hai phân thức `=` nhau
a: a^3+b^3+c^3-3abc
=(a+b)^3+c^3-3ab(a+b)-3bac
=(a+b+c)(a^2+2ab+b^2-ac-bc+c^2)-3ab(a+b+c)
=(a+b+c)(a^2+b^2+c^2-ab-ac-bc)
b: Đề sai rồi bạn
c: 2(a+b+c)*(b/2+c/2-a/2)
=(a+b+c)(b+c-a)
=(b+c)^2-a^2
=c^2+2bc+c^2-a^2
a) \(\left(a+b+c\right)\left(a^2+b^2+c^2-ab-bc-ac\right)\)
\(=\left(a+b+c\right)\left(a^2+b^2+c^2\right)-\left(a+b+c\right)\left(ab+bc+ac\right)\)
\(=a^3+ab^2+ac^2+a^2b+b^3+c^2b+a^2c+b^2c+c^3-a^2b-abc-a^2c-ab^2-b^2c-abc-abc-bc^2-ac^2\)
\(=a^3+b^3+c^3-3abc\left(đpcm\right)\)
b) Bạn chỉ cần nhân bung cả 2 vế ra là được á .
c) \(2\left(a+b+c\right)\left(\dfrac{b}{2}+\dfrac{c}{2}-\dfrac{a}{2}\right)\)
\(=2\left(a+b+c\right)\left(\dfrac{b+c-a}{2}\right)\)
\(=\left(a+b+c\right)\left(b+c-a\right)\)
\(=ab+ac-a^2+b^2+bc-ab+bc+c^2-ac\)
\(=2bc+b^2+c^2-a^2\left(đpcm\right)\)
Đề bài chỉ cho a+b+c=0 và yêu cầu cm ab + 2bc + 3ac < hoặc = 0
`(2bc-2016)/(3c-2bc+2016)`
`=(-(3c-2bc+2016)+3c)/(3c-2bc+2016)`
`=-1+(3c)/(3c-2bc+2016)`
`(2b)/(3-2b+ab)
`=(2bc)/(3c-2bc+abc)`
`=(2bc)/(3c-2bc+2016)`
`(4032-3ac)/(3ac-4032+2016a)`
`=(-(3ac-4032+2016a)+2016a)/(3ac-4032+2016a)`
`=-1+(2016a)/(3ac-2abc+2016a)`
`=-1+(2016)/(3c-2bc+2016)`
`=>M=-1+(3c)/(3c-2bc+2016)-(2bc)/(3c-2bc+2016)-1+(2016)/(3c-2bc+2016)
`=>M=-2+(3c-2bc+2016)/(3c-2bc+2016)`
`=>M=-2+1`
`=>M=-1`
`(2bc-2016)/(3c-2bc+2016)`
`=(-(3c-2bc+2016)+3c)/(3c-2bc+2016)`
`=-1+(3c)/(3c-2bc+2016)`
`(2b)/(3-2b+ab)`
`=(2bc)/(3c-2bc+abc)`
`=(2bc)/(3c-2bc+2016)`
`(4032-3ac)/(3ac-4032+2016a)`
`=(-(3ac-4032+2016a)+2016a)/(3ac-4032+2016a)`
`=-1+(2016a)/(3ac-2abc+2016a)`
`=-1+(2016)/(3c-2bc+2016)`
`=>M=-1+(3c)/(3c-2bc+2016)-(2bc)/(3c-2bc+2016)-1+(2016)/(3c-2bc+2016)`
`=>M=-2+(3c-2bc+2016)/(3c-2bc+2016)`
`=>M=-2+1`
`=>M=-1`
Nãy thiếu latex ạ sorry~~