Question

спростіть вираз:
1)7х(х-4)-х(6-х)=
2)5аb(4a+3b)-10a²(2b-4)=
3)xy(2x-11y)-x(xy+14y²)=
4)5c³(4c-3)-2c²(8c²-12)=​

Answer 1

$1) \ 7x(x-4)-x(6-x)=7x\cdot x+7x\cdot (-4)-x\cdot6-x\cdot(-x)=\\\\=7x^{2}-28x-6x+x^{2}=\boxed{8x^{2}-34x}$

$2) \ 5ab(4a+3b)-10a^{2}(2b-4)=5ab\cdot 4a+5ab\cdot3b-10a^2\cdot2b-10a^{2}\cdot(-4)=\\\\=20a^{2}b+15ab^{2}-20a^{2}b+40a^{2}=\boxed{40a^{2}+15ab^{2}}$

$3) \ xy(2x-11y)-x(xy+14y^{2})=xy\cdot2x+xy\cdot(-11y)-x\cdot xy-x\cdot14y^{2}=\\\\=2x^{2}y-11xy^{2}-x^{2}y-14xy^{2}=\boxed{x^{2}y-25xy^{2}}$

$4) \ 5c^{3}(4c-3)-2c^{2}(8c^{2}-12)=5c^{3}\cdot4c+5c^{3}\cdot(-3)-2c^{2}\cdot8c^{2}-2c^{2}\cdot(-12)=\\\\=20c^{4}-15c^{3}-16c^{4}+24c^{2}=\boxed{4c^{4}-15c^{3}+24c^{2}}$