Answer:
Step-by-step explanation:
Eliminate answer 4 immediately, because (4)(3) is not 7.
Look at answer 2: 7x + 3x = 10x, which does not match the middle term 12x in the original polynomial. Eliminate answer 2.
Look at answer 1: 1x + 21x = 22x, which does not match the middle term of the original polynomial. Eliminate answer 1.
All quadratics have solutions. Let's apply the quadratic formula to 3x^2 + 12x + 7: Here a = 3, b = 12 and c = 7, so that the discriminant b²-4ac is
12²-4(3)(7), or 144 - 84, or 60. Being positive, this tells us that the given poly has two real, unequal roots:
-12 ± √60 -12 + 2√15 -12 - 2√15
x = ----------------- = ------------------- and x = --------------------
3 3 3
Normally, if c is a root, then x - c is a factor.
If we try this here, however, the resulting factors do not at all match any of your answer choices.
Don't be offended...but please ensure you have copied this problem down correctly.
