Answer:
imaginary
Step-by-step explanation:

from the working strp, we know that the number is imaginary
we can't square root the negative number
Answer:
about 10
Step-by-step explanation:
62.8 = 2 pi r/2
62.8/2 = pi r
31.4/pi = pi r/pi
about 10 = r
Answer:
20
Step-by-step explanation:
We write what we know.
Jimmy
$50/mo app 65¢ or .65
Lisa
$55/mo app 40¢ or .40
a = number of apps
The difference will come from the number of apps, a.
We need them to equal each other so let's write an equation.
$50 + .65a = $55 + .40a
We need to solve for a.
$50 + .65a = $55 + .40a subtract $50 for each side.
$50 - $50 + .65a = $55 - $50 + .40a
.65a = $55 - $50 + .40a
.65a = $5 + .40a subtract .40a from each side
.65a - .40a = $5 + .40a - .40a
.65a - .40a = $5
.25a = $5 Divide each side by .25
.25a/.25 = $5/.25
a = $5/.25
a = 20
So Jimmy and Lisa need to download 20 apps for their bill to be the same.
The formula can be written in the form ...
... T = (original temperature) + x·(change in temperature each minute)
The problem statement gives you the original temperature (21 °C) and tells you the temperature after 12 minutes. You have to use that information to figure out the change in temperature each minute.
The change in temperature in 12 minutes is (75 °C) - (21 °C) = 54 °C. That is the change in 12 minutes, so the change in 1 minute will be 1/12 of that:
... 54/12 = 4.5
Using this value in the equation for T, we have
... T = 21 + 4.5x