a) \(4x\left(2x+1\right)-5x^2-6x\)
\(=8x^2+4x-5x^2-6x\)
\(=3x^2-2x\)
b) \(\left(x-2\right)\left(x+5\right)-x^2\)
\(=x\left(x+5\right)-2\left(x+5\right)-x^2\)
\(=x^2+5x-2x-10-x^2\)
\(=3x-10\)
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a,
\(4x\left(2x+1\right)-5x^2-6x\)
\(=8x^2+4x-5x^2-6x\)
\(=3x^2-2x\)
b.
\(\left(x-2\right)\left(x+5\right)-x^2\)
\(=x^2+5x-2x-10-x^2\)
\(=3x-10\)
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