Cho x-y=7 Tính:
B=\(x^3-3xy\left(x-y\right)-y^3-x^2+2xy-y^2\)
Những câu hỏi liên quan
Cho x-y=7
Tính:
a/ \(A=x^3-3xy\left(x-y\right)-y^3-x^2-2xy-y^2\)
b/ \(B=x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-95\)
Cho x-y=7
Tính
a/ \(A=x^3-3xy\left(x-y\right)-y^3-x^2-2xy-y^2\)
b/ \(B=x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-95\)
Cho \(x-y=7\). Tính giá trị của biểu thức:
\(A=x^3-y^3-21xy\)
\(B=x^3-3xy\left(x-y\right)-y^3-x^2+2xy-y^2\)
\(C=x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-95\)
\(A=x^3-y^3-21xy\)
\(A=\left(x-y\right).\left(x^2+xy+y^2\right)-21xy\)
\(A=7.\left(x^2+xy+y^2\right)-21xy\)
\(A=7.\left(x^2+xy+y^2+3xy\right)\)
\(A=7.\left(x^2+2xy+y^2+2xy\right)\)
\(A=7.\text{[}\left(x+y\right)^2+2xy\text{]}\)
\(A=7.\left(7^2+2xy\right)\)
\(A=7^3+14xy\)
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\(A=x^3-y^3-21xy\)
\(\Rightarrow A=\left(x-y\right)\left(x^2+xy+y^2\right)-21xy\)
\(\Rightarrow A=7\left(x^2+xy+y^2\right)-21xy\)
\(\Rightarrow A=7\left(x^2+xy+y^2-3xy\right)\)
\(\Rightarrow A=7\left(x^2+y^2-2xy\right)\)
\(\Rightarrow A=7\left(x-y\right)^2\)
\(\Rightarrow A=7.7^2\)
\(\Rightarrow A=7.49\)
\(\Rightarrow A=343\)
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Cho x-y=7.Tính:
a)x(x+2)+y(y-2)-2xy+37
b)\(x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-95\)
Cho x-y=7.Tính:
a)x(x+2)+y(y-2)-2xy+37
b)\(x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-95\)
a: \(=x^2+2x+y^2-2y-2xy+37\)
\(=\left(x-y\right)^2+2\left(x-y\right)+37\)
\(=7^2+2\cdot7+37=49+14+37=100\)
b: \(=x^3+x^2-y^3+y^2+xy-3xy\cdot\left(7+1\right)-95\)
\(=\left(x^3-y^3\right)+\left(x^2+y^2\right)+xy-24xy-95\)
\(=\left(x-y\right)^3+3xy\left(x-y\right)+\left(x-y\right)^2+2xy-23xy-95\)
\(=7^3+3xy\cdot7+49-21xy-95\)
\(=343+49-95=297\)
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Cho x-y=7, tính:
a) \(x\left(x+2\right)+y\left(y-2\right)-2xy+37\)
b) \(x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-95\)
a) \(x\left(x+2\right)+y\left(y-2\right)-2xy+37\)
\(=x^2+2x+y^2-2y-2xy+37\)
\(=\left(x^2-2xy+y^2\right)+2x-2y+37\)
\(=\left(x-y\right)^2+2\left(x-y\right)+37\)
\(=7^2+2.7+34\)
\(=100\)
b) \(x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-95\)
\(=x^3+x^2-y^3+y^2+xy-3xy-3xy\left(x-y\right)-95\)
\(=x^3+x^2-y^3+y^2-2xy-3xy\left(x-y\right)-95\)
\(=\left(x-y\right)^3+\left(x-y\right)^2-95\)
\(=7^3+7^2-95\)
\(=297\)
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Cho x+y=2
Tính A=x^3+y^3+3xy*(x+y)
B=x^2+2xy+y^2+4
C=x^3+y^3+3xy*(x+y)+7*(x+y)
A=x^3 + y^3 + 3xy(x+y)
=x+3x^y+3xy^2+y^3
=(x+y)^3=2^3=8
B=x^2+2xy+y^2+4
=(x+y)^2+4=4+4=8
C=x^3+y^3+3xy(x+y)+7(x+y)
=(x+y)^3+7(x+y)
=2^3+7.2
=8+14=22
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Cho x-y=7.Tính:
1)A=x(x+2)+y(y-2)-2xy+37
2)\(B=x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-9^5\)
\(A=x\left(x+2\right)+y\left(y-2\right)-2xy+37\)
\(A=x^2+2x+y^2-2y-2xy+37\)
\(A=\left(x^2+y^2-2xy+1+2x-2y\right)+36\)
\(A=\left(x-y+1\right)^2+36\)
\(A=\left(7+1\right)^2+36\)
\(A=8^2+36\)
\(A=100\)
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\(B=x^2\left(x+1\right)-y^2\left(y-1\right)+xy-3xy\left(x-y+1\right)-95\) \((9^5\) \(sai\)\()\)
\(B=x^3+x^2-y^3+y^2+xy-3x^2y+3xy^2-3xy-95\)
\(B=\left(x^3-3x^2y+3xy^2-y^3\right)+\left(x^2+xy-3xy+y^2\right)-95\)
\(B=\left(x-y\right)^3+\left(x^2-2xy+y^2\right)-95\)
\(B=\left(x-y\right)^3+\left(x-y\right)^2-95\)
\(B=7^3+7^2-95\)
\(B=297\)
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bài 1 tìm x biết
a)\(\left(3x-1\right)\left(2x+7\right)-\left(x+1\right)\left(6x-5\right)=\left(x+2\right)-\left(x-5\right)\)
b)\(3xy\left(x+y\right)-\left(x+y\right)\left(x^2+y^2+2xy\right)+y^3=27\)