### Home > CCA2 > Chapter 8 > Lesson 8.2.1 > Problem8-72

8-72.

If $f\left(x\right) = x^{2} + 7x − 9$, calculate the values in parts (a) through (c) below.

1. $f\left(−3\right)$

$f\left(−3\right) = −21$

1. $f\left(i\right)$

$f\left(i\right) = i^{2} + 7i − 9$

$f\left(i\right) = −10 + 7i$

1. $f\left(−3 + i\right)$

$f(-3+ i)= (-3+i)^2+7(-3 + i) - 9$

Use a generic rectangle to expand $\left(−3 + i\right)^{2}$.