Question

If f(x) is an even function and f(3)=5 then what is the value of 4f(3)+2f(-3)?

Answer 1

`4f(3)+2f(-3)=30`

Explanation:

We have been given that f(x) is an even function and f(3)=5. We are asked to find the value of 4f(3)+2f(-3).

Since we know that graph of an even function is symmetric with respect to y-axis. By the definition of an even function, a function f is even if and only if f(-x)=f(x) for all x in the domain of f.

Since we have been given that f(x) is an even function, so f(3)=f(-3).

Upon substituting our given values we will get,

`4f(3)+2f(-3)=4*5+2*5`

`4f(3)+2f(-3)=20+10`

`4f(3)+2f(-3)=30`

Therefore, the value of
`4f(3)+2f(-3)` will be 30.