SOLUTION: Suppose f(x) − f(x+1) = 3x2 and f(3) = 48, determine the value of f(5) 

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Question 1179883: Suppose f(x) − f(x+1) = 3x2 and f(3) = 48, determine the value of f(5) 
Found 2 solutions by amarjeeth123, ikleyn:
Answer by amarjeeth123(574)   (Show Source): You can put this solution on YOUR website!
We are given that f(x)-f(x+1)=3x^2
f(3)=48
Put x=3
We get f(3)-f(4)=3(3)^2
48-f(4)=27
f(4)=48-27=21
Put x=4 in the original equation
We get f(4)-f(5)=3(4)^2
21-f(5)=48
f(5)=21-48=-27
The value of f(5) is -27.
Answer by ikleyn(53763)   (Show Source): You can put this solution on YOUR website!
.

Re-write your equation in the form


    f(x+1) = f(x) - 3x^2.


This equation allows you to move one step forward and calculate f(x+1), as soon as you know x and f(x).


This formula is recursive and allows you to move as far in x-axis as you want.


So, if next time you will have similar assignment, you just know how to solve it.



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