Bài 1:
a, \(5x\left(x-2y\right)+2\left(2y-x\right)^2\)
\(=5x^2-10xy+2\left(4y^2-4xy+x^2\right)\)
\(=5x^2-10xy+8y^2-8xy+2x^2\)
\(=7x^2-18xy+8y^2\)
\(=7x^2-14xy-4xy+8y^2\)
\(=7x.\left(x-2y\right)-4y.\left(x-2y\right)=\left(x-2y\right).\left(7x-4y\right)\)
b, \(7x\left(y-4\right)^2-\left(4-y\right)^2\)
\(=7x.\left(y-4\right)^2-\left(y-4\right)^2\)
\(=\left(y-4\right)^2.\left(7x-1\right)\)
Chúc bạn học tốt!!!
Bài 2:
a, \(43^2+43.17=43.\left(43+17\right)=43.60\)
\(\Rightarrow43^2+43.17⋮60\)(đpcm)
b, \(27^5-3^{11}=\left(3^3\right)^5-3^{11}=3^{15}-3^{11}\\ =3^{11}.\left(3^4-1\right)=3^{11}.80\)
\(\Rightarrow27^5-3^{11}⋮80\) (đpcm)
Chúc bạn học tốt!!!
