Câu 1:
a: \(6x\left(x+y\right)+3y\left(y-2x\right)\)
\(=6x^2+6xy+3y^2-6xy=6x^2+3y^2\)
b: \(\left(18x^6y^5-12x^3y^4+6x^3y^3\right):\left(-3x^2y^3\right)\)
\(=-\dfrac{18x^6y^5}{3x^2y^3}+\dfrac{12x^3y^4}{3x^2y^3}-\dfrac{6x^3y^3}{3x^2y^3}\)
\(=-6x^4y^2+4xy-2x\)
c: \(\left(x+2y\right)^2-\left(x-4y\right)\left(x+y\right)\)
\(=x^2+4xy+4y^2-\left(x^2+xy-4xy-4y^2\right)\)
\(=x^2+4xy+4y^2-x^2+3xy+4y^2=8y^2+7xy\)
Câu 1:
a: \(8x\left(x+y\right)+2y\left(y-4x\right)\)
\(=8x^2+8xy+2y^2-8xy=8x^2+2y^2\)
b: \(\left(16x^5y^6-12x^3y^4+6x^3y^2\right):\left(-2x^2y^2\right)\)
\(=-\dfrac{16x^5y^6}{2x^2y^2}+\dfrac{12x^3y^4}{2x^2y^2}-\dfrac{6x^3y^2}{2x^2y^2}\)
\(=-8x^3y^4+6xy^2-3x\)
c: \(\left(2x+y\right)^2-\left(x-y\right)\left(4x+y\right)\)
\(=4x^2+4xy+y^2-\left(4x^2+xy-4xy-y^2\right)\)
\(=4x^2+4xy+y^2-4x^2+3xy+y^2=7xy+2y^2\)
Bài 1:
a: \(\left(2x-3\right)\left(x+5\right)-2x\left(x+1\right)\)
\(=2x^2+10x-3x-15-2x^2-2x\)
=5x-15
b: \(\left(10x^3y^2-5x^2y+15xy\right):5xy\)
\(=\dfrac{10x^3y^2}{5xy}-\dfrac{5x^2y}{5xy}+\dfrac{15xy}{5xy}\)
\(=2x^2y-x+3\)
c: \(\left(2x-3\right)^2-2x\left(2x+1\right)\)
\(=4x^2-12x+9-4x^2-2x\)
=-14x+9
