For khan academy math please answer, thank you!

7pi/theta = radius

Step-by-step explanation:

So we are using the arc length, central angle(in radians), and radius.

We know arc length, which is 7pi.

We don't know theta, which does not matter.

And finally, we don;t know radius, which is what we are looking for.

To find radius, we use:

arc length/theta=radius

Lets plug in our values:

7pi/theta=radius.

So the answer to the khan acadamy question is

7pi/∅

Here are some othr things that may help:

Radian * Radius = arc length

This solves for arc length

Here is another one:

Arc length/radius= radian

This solves for radians

Hope these help! :)

b.) 160 miles on a 5 gallons car

step-by-step explanation:

240/10=24 miles/gallon

160/5=32 miles/gallon

30/1=30 miles/gallon

168/6= 28 miles/gallon

32 miles/gallon is the most amount, so this is the best.

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15