Ta có :
\(36\left(a-b\right)^2-25\left(2a-1\right)^2\)
\(=\left[6\left(a-b\right)\right]^2-\left[5\left(2a-1\right)\right]^2\)
\(=\left[6\left(a-b\right)+5\left(2a-1\right)\right]\left[6\left(a-b\right)-5\left(2a-1\right)\right]\)
\(=\left(6a+6b+10a-5\right)\left(6a+6b-10a+5\right)\)
\(=\left(16a+6b-5\right)\left(6b-4a+5\right)\)