Bài 2:
1: \(9a^2+6a+1=\left(3a+1\right)^2\)
2: \(16x^2-8xy+y^2=\left(4x-y\right)^2\)
3: \(25x^2-40xy+16y^2=\left(5x-4y\right)^2\)
4: \(49a^2-154a+121=\left(7a-11\right)^2\)
5: \(x^2-x+\dfrac{1}{4}=\left(x-\dfrac{1}{2}\right)^2\)
Bài 1:
1: \(\left(2a+b\right)^2=4a^2+4ab+b^2\)
2: \(\left(a-3b\right)^2=a^2-6ab+9b^2\)
4: \(\left(3x-5y\right)^2=9x^2-30xy+25y^2\)
7: \(\left(3x-1\right)^2=9x^2-6x+1\)
9: \(\left(x+\dfrac{1}{2}\right)^2=x^2+x+\dfrac{1}{4}\)
10: \(\left(3x-\dfrac{1}{2}\right)^2=9x^2-3x+\dfrac{1}{4}\)
11: \(\left(4-\dfrac{1}{2}x\right)^2=16-4x+\dfrac{1}{4}x^2\)
12: \(\left(3x-0.5\right)^2=9x^2-3x+\dfrac{1}{4}\)
13: \(\left(4x-0.25\right)^2=16x^2-2x+\dfrac{1}{16}\)
