Question

${x}^{2} - 23x + 42$
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Answer 1

Answer:

${x}^{2} - 23x + 42 \\ \\ = {x}^{2} - 21x - 2 x + 42 \\ \\ = x(x - 21) - 2(x - 21) \\ \\ = (x - 21)(x - 2)$

Answer 2

Answer:

x=21

or

x=2

${x}^{2} - 23x + 42 = 0 \\ {x}^{2} - 21x - 2x + 42 = 0 \\ (x - 21)(x - 2) = 0 \\ x = 21 \\ x = 2$