Here are the solutions for questions 1 through 18:

1. $f(x) = -4x - 3$, find $f(-2)$:
   $f(-2) = -4(-2) - 3 = 8 - 3 = 5$

2. $f(x) = 3x$, find $f(-1)$:
   $f(-1) = 3(-1) = -3$

3. $f(x) = -4x + 2$, find $f(-1)$:
   $f(-1) = -4(-1) + 2 = 4 + 2 = 6$

4. $f(x) = -x + 5$, find $f(6)$:
   $f(6) = -6 + 5 = -1$

5. $f(x) = x^2 - 10x + 21$, find $f(4)$:
   $f(4) = 4^2 - 10(4) + 21 = 16 - 40 + 21 = -3$

6. $f(x) = -4x - 6$, find $f(0)$:
   $f(0) = -4(0) - 6 = -6$

7. $f(x) = x^2 - 6x + 3$, find $f(2)$:
   $f(2) = 2^2 - 6(2) + 3 = 4 - 12 + 3 = -5$

8. $f(x) = -x + 4$, find $f(6)$:
   $f(6) = -6 + 4 = -2$

9. $f(x) = 3x - 4$, find $f(-1)$:
   $f(-1) = 3(-1) - 4 = -3 - 4 = -7$

10. $f(x) = x^2 - 10x + 24$, find $f(7)$:
    $f(7) = 7^2 - 10(7) + 24 = 49 - 70 + 24 = 3$

11. $f(x) = -2x - 5$, find $f(5)$:
    $f(5) = -2(5) - 5 = -10 - 5 = -15$

12. $f(x) = -4x + 1$, find $f(0)$:
    $f(0) = -4(0) + 1 = 1$

13. $f(x) = -3x + 2$, find $f(-2)$:
    $f(-2) = -3(-2) + 2 = 6 + 2 = 8$

14. $f(x) = -3x - 1$, find $f(0)$:
    $f(0) = -3(0) - 1 = -1$

15. $f(x) = -4x - 1$, find $f(-2)$:
    $f(-2) = -4(-2) - 1 = 8 - 1 = 7$

16. $f(x) = x^2 - 8x + 16$, find $f(2)$:
    $f(2) = 2^2 - 8(2) + 16 = 4 - 16 + 16 = 4$

17. $f(x) = -4x - 4$, find $f(-1)$:
    $f(-1) = -4(-1) - 4 = 4 - 4 = 0$

18. $f(x) = 2x - 4$, find $f(-2)$:
    $f(-2) = 2(-2) - 4 = -4 - 4 = -8$

Would you like a breakdown of any of these solutions?

Here are five related questions to deepen your understanding:

1. How do you determine if a function is linear or quadratic?
2. What happens when you substitute a negative number into a function with an exponent?
3. How do you solve functions with fractions?
4. How do you graph quadratic functions from an equation?
5. What is function notation, and why is it useful?

Tip: Always double-check your substitution to avoid calculation errors.