Answer:
-2.5
Step-by-step explanation:
-30 + (-15) + (-20) + 55 = -10. Then you divide it by how many numbers there are (4). Which equals - 2.5. If this is wrong, then round up to -3.
He used an incorrect time ratio converting hours to minutes.
The only way to solve if it is equal to something
assuming that the teacher wanted you to make it equal to zero do
0=-3x^2-21x-54
remember if we can do
xy=0 then assume x and y=0
so factor
0=-3x^2-21x-54
undistribute the -3
0=-3(x^2+7x+18)
remember 0 times anything=0 so
x^2+7x+18 must equal zero
use quadratice formula which is
if you have
ax^2+bx+c=0 then
x=
![\frac{-b+/- \sqrt{b^{2}-4ac} }{2a}](https://tex.z-dn.net/?f=%20%5Cfrac%7B-b%2B%2F-%20%5Csqrt%7Bb%5E%7B2%7D-4ac%7D%20%7D%7B2a%7D%20)
x^2+7x+18
a=1
b=7
c=18
x=
![\frac{-7+/- \sqrt{7^{2}-4(1)(18)} }{2(1)}](https://tex.z-dn.net/?f=%20%5Cfrac%7B-7%2B%2F-%20%5Csqrt%7B7%5E%7B2%7D-4%281%29%2818%29%7D%20%7D%7B2%281%29%7D%20)
x=
![\frac{-7+/- \sqrt{49-72} }{2}](https://tex.z-dn.net/?f=%20%5Cfrac%7B-7%2B%2F-%20%5Csqrt%7B49-72%7D%20%7D%7B2%7D%20)
x=
![\frac{-7+/- \sqrt{-23} }{2}](https://tex.z-dn.net/?f=%20%5Cfrac%7B-7%2B%2F-%20%5Csqrt%7B-23%7D%20%7D%7B2%7D%20)
i=√-1
x=
![\frac{-7+/- i\sqrt{23} }{2}](https://tex.z-dn.net/?f=%20%5Cfrac%7B-7%2B%2F-%20i%5Csqrt%7B23%7D%20%7D%7B2%7D%20)
the zerose would be
x=
![\frac{-7+ i\sqrt{23} }{2}](https://tex.z-dn.net/?f=%20%5Cfrac%7B-7%2B%20i%5Csqrt%7B23%7D%20%7D%7B2%7D%20)
or
Answer:
6
Step-by-step explanation:
The circumference of a circle is ![2\pir](https://tex.z-dn.net/?f=2%5Cpir)
, so
. We can use this because the area of a circle is
. Thus,
.