The derivative of f(x) is f’(x) = ax^2 – (a+b)x
+c
Now the integral of f'(x) is
f(x).
Int[ f'x)] = Int [ (ax^2 – (a+b)x +c) dx
]
=Int [ (ax^2 ] - Int [(a+b)x] +
Int[c]
= ax^3/3 - ((a+b)/2)x^2 + cx
+C
Now f(x) = ax^3/3 - ((a+b)/2)x^2 + cx
+C
f(0) = 0
=> f(0) =
a*0^3/3 - ((a+b)/2)*0^2 + c*0 +C
=> 2 =
C
f(4) = 8
=> a*4^3/3 -
((a+b)/2)*4^2 + c*4 +2 =8
=> (a/3)*64 - ((a+b)/2)*16
+ c*4 +2 =8
=> (a/3)*32 - ((a+b)/2)*8 + c*2 +1
=4
=> (a/3)*32 - ((a+b)/2)*8 + c*2 -3 =
0
f(10) = 12
=>
a*10^3/3 - ((a+b)/2)*10^2 + c*10 +2 =12
=>
(a/3)*1000 - ((a+b)/2)*100 + c*10 +2 =12
=>
(a/3)*500 - ((a+b)/2)*50 + c*5 +1 =6
=> (a/3)*500 -
((a+b)/2)*50 + c*5 -5 = 0
=> (a/3)*100 -
((a+b)/2)*10 + c - 1 = 0
Now we have two equations
:
(a/3)*32 - ((a+b)/2)*8 + c*2 -3 =
0
(a/3)*100 - ((a+b)/2)*10 + c - 1 =
0
and 3 variables a, b and
c.
So we cannot find unique values for all of
them.
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