Question

Check my answer please

Answer 1

I put B

Answer 2

Did you use the quadratic formula ? or just guess ?

Answer 3

Well I saw that they both had + signs so 5 and 4 were the only positive

Answer 4

So an educated guess you could say.

Answer 5

There are a few things you could try
1) use the quadratic formula
2) try to factor the quadratic
3) test the choices they give you

Because you seem to be studying the quadratic formula, you might try it.
Option 3 means replace the x in the equation with an "answer" and see if you get 0 after you simplify it.

for example, you think 5 is one of the "zeros"
\[ x^2 + 9x + 20 \\
5^2 +9\cdot 5 + 20 \]
simplify. Do you get 0.... Not a chance!

Answer 6

if you use the quadratic formula,
a=1, b= 9, and c=20

now find
\[ \frac{-b ± \sqrt{b^2 - 4ac}}{2a} \]

Answer 7

Also it would be -5 and -4 because both work out to 0 and -9+- sqrt 45/2

Answer 8

-5 and -4 look good.
but your quadratic formula numbers look off.
-9 is ok
dividing the whole thing by 2 is ok
but inside the square root you should have
b*b -4*a*c where a=1, b= 9, and c=20
9*9 - 4*1*20

what do you get for 9*9 - 4*1*20 ?

Answer 9

ohhh -80