If f (x) = - 7x + 5x2 + 10, what does f (-2) equal?

All you have to do is replace x in the function with the number given. Remember that with f (x), (x) is the input and the equation is the "machine" that does something with the input, and then f (x), which is equal to the "machine", is your output so you can also say that f (x) is the same as y. So for the machine f (x) = 3x^2+5x-2, if you input - 2, you have: y=3 (-2) ^2+5 (-2) - 2 and then multiply:

y=3 (-2) ^2+5 (-2) - 2 Exponents are always first:

y=3 (4) + 5 (-2) - 2 Now multiply

y=12-10-2 subtract

y=0

F (x) = - 7x + 5x^2 + 10

f (x) = - 7 (-2) + 5 (-2) ^2 + 10

f (x) = 14 + 5 (4) + 10

f (x) = 14 + 20 + 10

f (x) = 44