Question

the function y=f(x) is y=ax^3+2x^2 +bx. if the function has a max T.P at (3,36)..determine a and b values

Answer 1

first find f'(x)
can you do that?

Answer 2

first find f'(x)
can you do that?

Answer 3

yes..so...3ax^2+4x+b

Answer 4

right
this = 0 at a TP

so 3a(3(^2 + 12 + b = 0
27a + b + 12 = 0

Answer 5

gotta go for a minute

Answer 6

gotta go for a minute

Answer 7

hmm...so i use elimination or substitution method to solve for a and b?

Answer 8

you need another equation in a and b
substitute y=36 and x = 3 into f(x):

36 = (3^3) a + 2(3)^2 + 3b

Answer 9

you need another equation in a and b
substitute y=36 and x = 3 into f(x):

36 = (3^3) a + 2(3)^2 + 3b

Answer 10

ok....thanks..i get it now

Answer 11

yw