Question

The sum of two trinomials is 7x2 - 5x + 4. if one of the trinomials is 3x2 + 2x - 1, then what is the other trinomial?

a.
10x2 - 3x + 3
b.
4x2 - 7x + 5
c.
10x2 + 7x + 5
d.
4x2 - 3x + 3

Answer 1

b. 4x^2 -7x +5

Explanation:

When you know a sum and one of its contributors, you can find the other by subtraction. The other trinomial is ...

(7x^2 -5x +4) - (3x^2 +2x -1)

= (7 -3)x^2 +(-5 -2)x +(4 -(-1))

= 4x^2 -7x +5 . . . . . matches B