Question

Add the following polynomials, then place the answer in the proper location on the grid. Write the answer in descending powers of a. Add: 2a3 + 5a - 7 and 5a2 - 6a + 12

Answer 1

Combine  2a^3+5a-7 and 5a^2-6a+12.

Rewrite this so that the second expression is beneath the first:

2a^3+5a-7 
5a^2-6a+12

Combine like terms.  The highest order term is 2a^3:

2a^3+0a^2 +5a-7 
        +5a^2 - 6a+12
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2a^3 + 5a^2 - a + 5 (answer)

Note how these terms are in descending order by power of a.