Q2 of 64 Page 43

Find the zeros of the following quadratic polynomials:

p(x) = x2 + 4x — 21

Here p(x) = x2 + 4x – 21


To find the zeros of p(x), let p(x) = 0


∴ x2 + 4x – 21 = 0


∴ x2 + 7x – 3x – 21 = 0


∴ x(x + 7) – 3(x + 7) = 0


∴ (x + 7)(x – 3) = 0


∴ x = –7 or x = 3


⇒ –7 and 3 are the zeros of the quadratic polynomial p(x).


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