Answer:
see explanation
Explanation:
(8)
the equation of a circle centred at the origin is
x² + y² = r² ( r is the radius )
x² + y² = 49 ← is in this form
with r² = 49 ( take square root of both sides )
r =
= 7
(9)
given x is directly proportional to y then the equation relating them is
y = kx ← k is the constant of proportionality
to find k use the condition when x = 4 , y = 9 , then
9 = 4k ( divide both sides by 4 )
= k = 2.25
Then
y = 2.25x ← equation for y in terms of x