\(a)\) \({x^2} + 4x + 3\)
\( = {x^2} + x + 3x + 3 \)
\(= \left( {{x^2} + x} \right) + \left( {3x + 3} \right)\)
\(=x\left( {x + 1} \right) + 3\left( {x + 1} \right) \)
\(= \left( {x + 1} \right)\left( {x + 3} \right)\)
\(b)\) \(2{x^2} + 3x – 5\)
\( = 2{x^2} - 2x + 5x - 5\)
\( = \left( {2{x^2} - 2x} \right) + \left( {5x - 5} \right)\)
\( = 2x\left( {x - 1} \right) + 5\left( {x - 1} \right)\)
\( = \left( {x - 1} \right)\left( {2x + 5} \right)\)
\(c)\) \(16x - 5{x^2} – 3\)
\( = 15x - 5{x^2} - 3 + x \)
\(= \left( {15x - 5{x^2}} \right) - \left( {3 - x} \right)\)
\( = 5x\left( {3 - x} \right) - \left( {3 - x} \right) \)
\(= \left( {3 - x} \right)\left( {5x - 1} \right)\)
