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Question
Show that x – 2 is a factor of 5x2 + 15x – 50.
Solution
(x – a) is a factor of a polynomial f(x) if the remainder, when f(x) is divided by (x – a), is 0, i.e., if f(a) = 0.
f(x) = 5x2 + 15x – 50
f(2) = 5(2)2 + 15(2) – 50
= 20 + 30 – 50
= 0
Hence, x – 2 is a factor of 5x2 + 15x – 50
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