Question

[chủ nick đg bận :)))]

 lm giúp mik vs chiều nay kt r

Answer 1

[Nguyễn Lê Phước Thịnh]

Bài 4:

Ta có: \(\left(n+2\right)^2-\left(n-2\right)^2\)

\(=n^2+4n+4-n^2+4n-4\)

\(=8n⋮8\)

Answer 2

[Nguyễn Lê Phước Thịnh]

Bài 1: 

a: \(x^2-12x+36=\left(x-6\right)^2\)

b: \(4x^2+12x+9=\left(2x+3\right)^2\)

c: \(\dfrac{1}{4}x^2-5xy+25y^2=\left(\dfrac{1}{2}x-5y\right)^2\)

d: \(\left(x-5\right)^2-16=\left(x-5-4\right)\left(x-5+4\right)=\left(x-9\right)\left(x-1\right)\)

e: \(25-\left(3-x\right)^2=\left(5-3+x\right)\left(5+3-x\right)=\left(x+2\right)\left(8-x\right)\)

g: \(\left(7x-4\right)^2-\left(2x+1\right)^2\)

\(=\left(7x-4-2x-1\right)\left(7x-4+2x+1\right)\)

\(=\left(5x-5\right)\left(9x-3\right)\)

\(=15\left(x-1\right)\left(3x-1\right)\)

f: \(8x^3+\dfrac{1}{27}=\left(2x+\dfrac{1}{3}\right)\left(4x^2-\dfrac{2}{3}x+\dfrac{1}{9}\right)\)

g: \(49\left(x-4\right)^2-9\left(x+2\right)^2\)

\(=\left(7x-28-3x-6\right)\left(7x-28+3x+6\right)\)

\(=\left(4x-34\right)\left(10x-24\right)\)

\(=4\left(2x-17\right)\left(5x-12\right)\)