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EXERCISE 8 A Q.36
Q.36) If f(x) = x2 – 6x+8 then f’(5) – f’(8) is equal to

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f(x) = x2 – 6x + 8
Diff.w.r.t. x we get
f'(x) = 2x - 6
f'(2) = 2(2) - 6 = 4 - 6 = -2
f'(5) = 2(5) - 6 = 10 - 6 = 4
f'(8) = 2 (8) - 6 = 16 - 6 = 10
Now f'(5) - f'(8) = 4 - 10 = -6
= 3 × -2
= 3f'(2).
Answer : (b)