1: \(4x^2-25-\left(2x+7\right)\left(2x-5\right)\)
\(=\left(2x-5\right)\left(2x+5\right)-\left(2x+7\right)\left(2x-5\right)\)
\(=\left(2x-5\right)\left(2x+5-2x-7\right)\)
=-2(2x-5)
2: \(3\left(x+4\right)-x^2-4x\)
\(=3\left(x+4\right)-x\left(x+4\right)\)
\(=\left(x+4\right)\left(3-x\right)\)