Question

[Nguyễn Quang]

Bài 1: Tính:

a) (x+2y)²

b) (3x-2y)²

c) (2x - \(\dfrac{1}{2}\))³

d) (\(\dfrac{x}{2}\) - y)(\(\dfrac{x}{2}\)+ y)

Bài 2: Viết các biểu thức sau dưới dạng tích

a) x⁴ + 4x² + 4

b) 4a²b² - c²d²

Answer 1

[Phạm Tuấn Đạt]

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

\(b,\left(3x-2y\right)^2=9x^2-12xy+4y^2\)

\(c,\left(2x-\dfrac{1}{2}\right)^3=8x^3-3.4x^2.\dfrac{1}{2}+3.2x.\dfrac{1}{4}-\dfrac{1}{8}=8x^3-6x^2+\dfrac{3}{2}x-\dfrac{1}{8}\)

\(d,\left(\dfrac{x}{2}-y\right)\left(\dfrac{x}{2}+y\right)=\dfrac{x^2}{4}-y^2\)

\(2;a,x^4+4x^2+4\)

\(=\left(x^2+2\right)^2\)

\(b,4a^2b^2-c^2d^2\)

\(=\left(2ab\right)^2-\left(cd\right)^2\)

\(=\left(2ab-cd\right)\left(2ab+cd\right)\)