SA=4pir^2
78.54km^2=SA
78.54=4pir^2
divide both sides by 4
19.635=pir^2
aprox pi=3.14 so divide both sides by 3.14
6.25318=r^2
sqrt both sides
2.50063=r
round
radius=2.5km
this question is flawed in that it gives the wrong units
answer is the option with 2.5 in it
2nd one
Step-by-step explanation:
If it's a straight line the use formula

m= gradient of line
c = y-intercept
we know that y-intercept is 4 so coordinate is
(0,4)
Equation also passes (2,10)
Use both coordinate to find gradient
m= vertical distance / horizontal distance
= (10-4) / (2-0)
= 3
y = 3x + 4
Answer:
The equation representing the relationships between the cost of laptop and Cole's payment is
.
Step-by-step explanation:
Given:
Cost of laptop = 335
Down payments = $50
Number of equal payments = 
We need to write the equation form the relationships between the cost of laptop and cole's payment.
Solution:
Now we can say that;
Cost of laptop is equal to sum of Down payments and Number of equal payments.
framing in equation form we get;

Hence The equation representing the relationships between the cost of laptop and Cole's payment is
.