Write an equation of the direct variation that includes the given point (-8, -4)
Direct variation is y= kx for some constant k
Find k using the point (-8,-4)
y=kx
(-4)=k(-8) substitution
-4/-8=k(-8/-8) division property
1/2=k
equation of direct variation is y=1/2k
Answer:
d
Step-by-step explanation:
Given y is directly proportional to x² then the equation relating them is
y = kx² ← k is the constant of proportion
To find k use the condition y = 
when x = 
, then
= k( )² = 
k ( multiply both sides by 8 )
1 = 2k ( divide both sides by 2 )
k =
y = x² ← equation of proportion
When y = 
, then
= x² ( multiply both sides by 2 )
9 = x² ( take the square root of both sides )
x = ± 
= ± 3
with positive value x = 3 → d
The like terms are 12 and 5, so you have to subtract 5 from both sides.
12 < x + 5
-5. -5
7 < x
We can just switch it around so x is in the left side.
x > 7
