Question

2. Tính

a. (x-2y)^2

b. (2x^2 + 3) ^2

c. ( x-2 ) ( x^2 +2x+4 )

d. (2x-1)^3

Answer 1

\(a,\left(x-2y\right)^2=x^2-2.x.2y+\left(2y\right)^2=x^2-4xy+4y^2\)

\(b,\left(2x^2+3\right)^2=\left(2x^2\right)^2+2.2x^2.3+3^2=4x^4+12x^2+9\)

\(c,\left(x-2\right)\left(x^2+2x+4\right)=\left(x-2\right)\left(x^2+2.x+2^2\right)=x^3-2^3=x^3-8\)

\(d,\left(2x-1\right)^3=\left(2x\right)^3-3.\left(2x\right)^2.1+3.2x.1^2-1^3=8x^3-12x+6x-1\)

Answer 2

Giải:

a) \(\left(x-2y\right)^2=x^2-4xy+4y^2\)

b) \(\left(2x^2+3\right)^2=4x^4+12x^2+9\)

c) \(\left(x-2\right)\left(x^2+2x+4\right)=x^3-8\)

d) \(\left(2x-1\right)^3=8x^3-12x+6x-1\)

Chúc bạn học tốt!