If f(x) = -3x2 + 7, find f(-3).

Question

 Please help i am very confused!

Answer 1

Hello Jeffery,

 

Don't get discouraged! I'm sure the f(x) part is throwing you off. f(x) is the same as saying "a function of x". 

Up until now, you've probably been using y as your independent variable (for every x value, there was a different y value). f(x) is the exact same thing. All it's saying is that when I plug in any number for x, I get a value---the function of x. 

 

In our problem, it's asking you what the function will be if x=-3. We will then plug -3 into our equation and see what we get out. 

 

f(-3)=-3(-3)²+7

 

Remember to do the exponent first! 

f(-3)=-3(9)+7

f(-3)=-27+7

f(-3)=-20