If the function f(x) is differentiable

and

f(x) =

ax^3 - 6x ; x <= 1

bx^2 + 4 ; x > 1

then a =

A) 0

B) 1

C) -14

D) -24

E) 26

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- January 13th 2008, 09:17 AMDINOCALC09differentiable function
If the function f(x) is differentiable

and

f(x) =

ax^3 - 6x ; x <= 1

bx^2 + 4 ; x > 1

then a =

A) 0

B) 1

C) -14

D) -24

E) 26 - January 13th 2008, 01:42 PMCaptainBlack
- January 15th 2008, 01:44 AMDINOCALC09
is the answer C

- January 15th 2008, 02:10 AMearboth
- January 15th 2008, 04:30 AMcolby2152
Yes, the answer is C because as CaptainBlack said, to be differentiable, a function must be continuous, and therefore its derivatives should have values and be continuous. This gives you two equations with two unknowns. You probably had the f(x) values equal to each other at one, but you may have not realized that f'(x) should be continuous at that point as well.