Mathematics
x2 - 23x + 42 is equal to :
(x - 21) (x + 2)
(x - 21) (x - 2)
(x + 21) (x + 2)
(x + 21) (x - 2)
Factorisation
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Answer
x2 - 23x + 42
= x2 - (21 + 2)x + 42
= x2 - 21x - 2x + 42
= (x2 - 21x) - 2(2x - 42)
= x (x - 21) - 2(x - 21)
= (x - 21)(x - 2)
Hence, option 2 is the correct option.
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