Question

Помогите c алгеброй пж очень надо

Answer 1

$\tt 1.~~ a)\,(2a-1)^2=(2a)^2-2\cdot2a\cdot1+1^2=4a^2-4a+1\\ b)~(x+3y)^2=x^2+2\cdot x\cdot 3y+(3y)^2=x^2+6xy+9y^2\\ c)~ (0.2x-y)(0.2x+y)=(0.2x)^2-y^2=0.04x^2-y^2$

$\tt 2.~ a)~ (c-2)(c+3)-(c-1)^2=c^2-2c+3c-6-(c^2-2c+1)=\\ =c^2+c-6-c^2+2c-1=3c-7\\ \\ b)~ 3(a+c)^2-6ac=3(a^2+2ac+c^2)-6ac=3a^2+6ac+3c^2-6ac=\\ =3a^2+3c^2=3(a^2+c^2)\\ \\ c)~ (p-3)(p^2+3p+9)-p^3=p^3-3^3-p^3=p^3-27-p^3=-27$

$\tt 3.~ (12a^3-3a^2b):3a=3a^2(4a-b):3a=a(4a-b)$

Если а = -2 и b = 10, то $\tt a(4a-b)=(-2)\cdot(4\cdot(-2)-10)=36$