It is given that A is directly proportional to r2 and r> 0. When r=5, A=75. Find
(a)the value of A when r=4,
(b)the value of r when A=147

see explanation

Step-by-step explanation:

Given A is directly proportional to r² then the equation relating them is

A = kr² ← k is the constant of proportion

To find k use the condition when r = 5, A = 75 , then

75 = k × 5² = 25k ( divide both sides by 25 )

3 = k

A = 3r² ← equation of proportion

(a)

when r = 4, then

A = 3 × 4² = 3 × 16 = 48

(b)

when A = 147 , then

147 = 3r² ( divide both sides by 3 )

49 = r² ( take the square root of both sides )

r = = 7

0.32

step-by-step explanation:

2.24/7

(1, –1), (16, –4), (36, –6)

step-by-step explanation:

given that the function is

this can also be written as

we have to graph this function and check which list of points lie on the graph

see attachment for graph:

we find that the points lying are (1,-1) (16,-4) and (36,-6)

since square root is there we find that x can only be posiitve but y can be since square root both positive and negative.