\(a)\) \({x^2} + 5x -6\)
\( = {x^2} - x + 6x - 6 \)
\(= \left( {{x^2} - x} \right) + \left( {6x - 6} \right)\)
\( = x\left( {x - 1} \right) + 6\left( {x - 1} \right)\)
\(= \left( {x - 1} \right)\left( {x + 6} \right)\)
\(b)\) \(5{x^2} + 5xy - x - y\)
\( = \left( {5{x^2} + 5xy} \right) - \left( {x + y} \right) \)
\(= 5x\left( {x + y} \right) - \left( {x + y} \right)\)
\( = \left( {x + y} \right)\left( {5x - 1} \right)\)
\(c)\) \(7x - 6{x^2} – 2\)
\( = 4x - 6{x^2} - 2 + 3x \)
\(= \left( {4x - 6{x^2}} \right) - \left( {2 - 3x} \right)\)
\( = 2x\left( {2 - 3x} \right) - \left( {2 - 3x} \right) \)
\(= \left( {2 - 3x} \right)\left( {2x - 1} \right)\)
