Phân tích đa thức thành nhân tử:
23). \(\left(2a-b\right)^2-4\left(a-b\right)^2\)
24). \(9\left(a+b\right)^2-4\left(a-2b\right)^2\)
25). \(4\left(2a-b\right)^2-16\left(a-b\right)^2\)
26). \(36\left(x-y\right)^2-25\left(2x-1\right)^2\)
27). \(\left(x^2+1\right)^2-4x^2\)
28). \(16x^2-\left(x^2+4\right)\)
29). \(\left(4x^2+\dfrac{1}{4}\right)-4x^2\)
30). \(\left(4x^2+1\right)^2-16x^2\)
23: \(=\left(2a-b\right)^2-\left(2a-2b\right)^2\)
\(=\left(2a-b-2a+2b\right)\left(2a-b+2a-2b\right)\)
\(=b\left(4a-3b\right)\)
24: \(=\left(3a+3b\right)^2-\left(2a-4b\right)^2\)
\(=\left(3a+3b-2a+4b\right)\left(3a+3b+2a-4b\right)\)
\(=\left(a+7b\right)\left(5a-b\right)\)
25: \(=\left(4a-2b\right)^2-\left(4a-4b\right)^2\)
\(=\left(4a-2b-4a+4b\right)\left(4a-2b+4a-4b\right)\)
\(=2b\left(8a-6b\right)\)
=4b(4a-3b)
