21x = 196 – x2


(viii) 21x = 196 – x2

Sol. 21x = 196 – x2

x2 + 21x – 196 = 0

x2 – 28x – 7x – 196 = 0

x (x + 28) – 7 (x + 28) = 0

(x + 28) (x – 7) = 0

x + 28 = 0 or x – 7 = 0


x = –28 or x = 7


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