Answer:
D 17 1/4
Step-by-step explanation:
There are no zeroes for an expression, only for equations.
Assuming equation to be
<span>−7x^2 − 91x − 280=0
-7(x^2+13x+40)=0
-7(x+8)(x+5)=0
by the zero product properties,
x+8=0 => x=-8
or
x+5=0 => x=-5</span>
<u>Answer:</u>
a = 8.1
<u>Step-by-step explanation:</u>
Use the cosine rule:

Substituting the values:

⇒ 
⇒ 
The third set of angles is complementary. Complementary angles are angles that add up to 90°.
56° + 34° = 90°