Determine whether f(x) = 3x^4 - 5x^2 + 2 is even odd or neither.

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justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

We have to find if f(x) = 3x^4 - 5x^2 + 2 is even or odd.

Now for even function we know that f(-x) = f(x).

Here for f(x) = 3x^4 - 5x^2 + 2 we see that

f(-x) = 3*(-x)^4 - 5(-x)^2 + 2

as for any number raised x raised to an even power n, x^n = (-x)^n

=> 3*x^4 - 5x^2 + 2

=> f(x)

Therefore as the function has only even powers of x we can see that it is an even function.

Top Answer

giorgiana1976's profile pic

giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted on

A function is even if

f(-x) = f(x)

In other words, plugging in a number will be the same as plugging in the negative value of the same number.

We'll analyze the given function, replacing each x by -x.

f(-x) = 3(-x)^4 - 5(-x)^2 + 2 

We'll compute raising -x to the 4th and 2nd powers and we'll get:

(-x)^4 = (-x)(-x)(-x)(-x) = x^2*x^2 = x^4

f(-x) = 3(x)^4 - 5(x)^2 + 2 

So we can see that:

f(-x) = f(x) which means that the function f(x) is an even function. 

An even function has symmetry across the y-axis. We also know that if all of the exponents are even, then the function is even.

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