Question

The sum of 2 trinomials is 7x^2 - 5x + 4. If one of the trinomials is 3x^2 + 2x - 1, then what is the other trinomial?

A. 10x^2 + 7x + 5
B. 4x^2 - 3x + 3
C. 4x^2 -7x + 5
D. 10x^2 - 3x + 3

Answer 1

We can subtract the sum of the two trinomials by one of the trinomials.
(7x²-5x+4)-(3x²+2x-1)
Let's look at each part.
7x²-3x²=4x²
-5x-2x=-7x
4-(-1)=5
So, the trinomial should look like:
4x²-7x+5
So, C. 4x²-7x+5 is the other trinomial.