For the differentiable function f:R−0→R, let 3f(x)+2f(x1)=x1−10, then ∣f(3)+f′(41)∣ is equal to
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Official solution
Given the equation: 3f(x)+2f(x1)=x1−10
Replace x with x1 in the original equation:
3f(x1)+2f(x)=x−10
Now, we have two equations:
3f(x)+2f(x1)=x1−103f(x1)+2f(x)=x−10
By adding the two equations, we can find f(x):
5f(x)=x3−2x−10
Now, let's differentiate both sides with respect to x:
5f′(x)=−x23−2
Now, we can find the values for f(3) and f′(41):
f(3)=51(1−6−10)=−3f′(41)=51(−48−2)=−10
Finally, calculate the expression we are interested in :
∣f(3)+f′(41)∣=∣−3−10∣=13