Asked by Nathan
Given the function f(x) = ax^3 + bx^2 + 3x - 2,
and f(2) = 10 and f ' (-1) = 14,
solve for A and B.
and f(2) = 10 and f ' (-1) = 14,
solve for A and B.
Answers
Answered by
Reiny
f(x) = ax^3 + bx^2 + 3x - 2
f'(x) = 3ax^2 + 2bx + 3
f'(-1) = 3a - 2b + 3 = 14
3a - 2b = 11 **
also f(2) = 10
8a + 4b + 6 - 2 = 10
8a + 4b = 6
4a + 2b = 3 ***
add ** and ***
7a = 14
a = 2 , put that back into ** to find b
f'(x) = 3ax^2 + 2bx + 3
f'(-1) = 3a - 2b + 3 = 14
3a - 2b = 11 **
also f(2) = 10
8a + 4b + 6 - 2 = 10
8a + 4b = 6
4a + 2b = 3 ***
add ** and ***
7a = 14
a = 2 , put that back into ** to find b