Bài 17:
1) \(3^2-x^2=\left(3-x\right)\left(3+x\right)\)
2) \(x^2-36=\left(x-6\right)\left(x+6\right)\)
3) \(y^2-1=\left(y-1\right)\left(y+1\right)\)
4) \(25-y^2=\left(5-y\right)\left(5+y\right)\)
5) \(9x^2-1=\left(3x-1\right)\left(3x+1\right)\)
6) \(\dfrac{1}{25}-4x^2=\left(\dfrac{1}{5}-2x\right)\left(\dfrac{1}{5}+2x\right)\)
7) \(9x^2-y^2=\left(3x-y\right)\left(3x+y\right)\)
8) \(x^2-4y^2=\left(x-2y\right)\left(x+2y\right)\)
Bài 18:
1) \(\left(x-5\right)\left(x+5\right)=x^2-25\)
2) \(\left(4-x\right)\left(4+x\right)=16-x^2\)
3) \(\left(x-\dfrac{2}{3}\right)\left(x+\dfrac{2}{3}\right)=x^2-\dfrac{4}{9}\)
4) \(\left(1+2x\right)\left(1-2x\right)=1-4x^2\)
5) \(-\left(2x+3\right)\left(3-2x\right)=\left(2x+3\right)\left(2x-3\right)=4x^2-9\)
6) \(-\left(5x-3\right)\left(3+5x\right)=\left(3-5x\right)\left(3+5x\right)=9-25x^2\)
7) \(-\left(3x-\dfrac{2}{5}\right)\left(3x+\dfrac{2}{5}\right)=-\left(9x^2-\dfrac{4}{25}\right)=\dfrac{4}{25}-9x^2\)
8) \(-\left(2x-\dfrac{2}{3}\right)\left(2x+\dfrac{2}{3}\right)=-\left(4x^2-\dfrac{4}{9}\right)=\dfrac{4}{9}-4x^2\)
1)\(\left(x+2\right)^2\)
2)\(\left(x+3\right)^2\)
3)\(\left(2x+1\right)^2\)
4)\(\left(3+2x\right)^2\)
5)\(\left(x-1\right)^2\)
6)\(\left(x-4\right)^2\)
7)\(\left(6-x\right)^2\)
8)\(\left(2x-3y\right)^2\)
9)\(\left(3x-1\right)^2\)
Bài 16:
1) \(x^2+4x+4=\left(x+2\right)^2\)
2) \(x^2+6x+9=\left(x+3\right)^2\)
3) \(4x^2+4x+1=\left(2x+1\right)^2\)
4) \(4x^2+12x+9=\left(2x+3\right)^2\)
5) \(x^2-2x+1=\left(x-1\right)^2\)
6) \(x^2-8x+16=\left(x-4\right)^2\)
7) \(x^2-12x+36=\left(x-6\right)^2\)
8) \(4x^2-12xy+9y^2=\left(2x-3y\right)^2\)
9) \(9x^2-6x+1=\left(3x-1\right)^2\)
10) \(4x^2+12x+9=\left(2x+3\right)^2\)
Bài 16:
11) \(x^2+3x+\dfrac{9}{4}=\left(x+\dfrac{3}{2}\right)^2\)
12) \(4x^2-6x+\dfrac{9}{4}=\left(2x-\dfrac{3}{2}\right)^2\)