Answer :

To solve the expression [tex]\(a^4 + a^3 - a^2\)[/tex], we need to evaluate each term step by step for any given value of [tex]\(a\)[/tex]. Here's a detailed breakdown:

1. Calculate [tex]\(a^4\)[/tex] (a raised to the fourth power):
[tex]\[ a^4 = a \times a \times a \times a \][/tex]

2. Calculate [tex]\(a^3\)[/tex] (a raised to the third power):
[tex]\[ a^3 = a \times a \times a \][/tex]

3. Calculate [tex]\(a^2\)[/tex] (a raised to the second power):
[tex]\[ a^2 = a \times a \][/tex]

4. Substitute these values back into the expression:
[tex]\[ a^4 + a^3 - a^2 \][/tex]

### Example Calculation

Let's take an example where [tex]\(a = 2\)[/tex]:

1. Calculate [tex]\(2^4\)[/tex]:
[tex]\[ 2^4 = 2 \times 2 \times 2 \times 2 = 16 \][/tex]

2. Calculate [tex]\(2^3\)[/tex]:
[tex]\[ 2^3 = 2 \times 2 \times 2 = 8 \][/tex]

3. Calculate [tex]\(2^2\)[/tex]:
[tex]\[ 2^2 = 2 \times 2 = 4 \][/tex]

4. Substitute these values back into the expression:
[tex]\[ a^4 + a^3 - a^2 = 16 + 8 - 4 \][/tex]

5. Simplify the expression:
[tex]\[ 16 + 8 - 4 = 20 \][/tex]

So, for [tex]\(a = 2\)[/tex], the value of the expression [tex]\(a^4 + a^3 - a^2\)[/tex] is 20.

### General Solution

For any value of [tex]\(a\)[/tex], you can follow the same steps:

1. Compute [tex]\(a^4\)[/tex].
2. Compute [tex]\(a^3\)[/tex].
3. Compute [tex]\(a^2\)[/tex].
4. Add the results of [tex]\(a^4\)[/tex] and [tex]\(a^3\)[/tex].
5. Subtract [tex]\(a^2\)[/tex] from the result of step 4.

This will give you the value of the expression [tex]\(a^4 + a^3 - a^2\)[/tex] for any input [tex]\(a\)[/tex].