If f(x) = 2x² - 30, find f(4).
35, -14, 2, 17

Solution:

The given function is :

f(x) = 2x² - 30

To find f(4) the value of variable x has to substituted with 4 in the function.

Therefore

f(4) = 2(4)² - 30

= 2(16) - 30

= 32 - 30

= 2

Another example of such type will be: if f(x) = 8x² - 4x + 2 then find f(2)?

Replacing x by 2 we get f(2) = 8(2)² - 4(2) + 2

= 8(16) - 8 + 2

= 128 - 8 + 2

= 122

---

If f(x) = 2x² - 30, find f(4).
35, -14, 2, 17

Summary:

If f(x) = 2x² - 30, then f(4) = 2.