Question
The sum of a positive number 'A' and its square is 420.
Find the value of (A2 - 7A).Solution
ATQ; A + A2 = 420 Or, A2 + A - 420 = 0 Or, A2 + 21A - 20A - 420 = 0 Or, (A + 21)(A - 20) = 0 So, A = 20 or A = -21 Since, 'A' is positive. So, required value = 202 - 20 × 7 = 400 - 140 = 260
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