Question

Write each of the following expressions without using absolute value. |z−7|−|z−9|, if z<7

Answer 1

-2

Explanation:

z - 7 ≥ 0

z ≥ 7

| z - 7 | = z - 7, z ≥ 7

| z - 7 | = -z + 7, z < 7

z - 9 ≥ 0

z ≥ 9

| z - 9 | = z - 9, z ≥ 9

| z - 9 | = -z + 9, z < 9

| z - 7 | = -z + 7

| z - 9 | = -z + 9

|z - 7| - |z - 9|

-z + 7 - (-z + 9)

-z + 7 + z - 9

= -2