a) \(\left(x-3\right)\left(x+7\right)-\left(2x-5\right)\left(x-1\right)\)
\(=\left(x^2-3x+7x-21\right)-\left(2x^2-5x-2x+5\right)\)
\(=\left(x^2+4x-21\right)-\left(2x^2-7x+5\right)\)
\(=x^2+4x-21-2x^2+7x-5\)
\(=-x^2+11x-26\)
b) \(-\left(3x+5\right)\left(2x-1\right)-\left[1-4\left(3x+2\right)\right]\)
\(=-\left(6x^2+10x-3x-5\right)-\left(1-12x-8\right)\)
\(=-\left(6x^2+7x-5\right)-\left(1-12x-8\right)\)
\(=-6x^2-4x+5-1+12x+8\)
\(=-6x^2+8x+12\)
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