Question 1054336
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For all real values of x, f(x^2) + f(30-x)=6x-4. Determine the value of f(25).
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Apply the given equality {{{f(x^2) + f(30-x)}}} = {{{6x-4}}}

to x = 5. You will get then


f(25) + f(30-5) = 6*5-4,   or

f(25) + f(25) = 26,   or

2*f(25) = 26,   which gives  f(25) = {{{26/2}}} = 13.

<U>Answer</U>.  f(25) = 13.
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