Y is partly constant and partly varies as X and when X=5,Y=8 and when X=6,Y=4.
(A)find the equation connecting Y and X.
(B)find y when X=15.
(C)find X when Y =20.
3 answers
?
y = kx + c
when X=5,Y=8
8 = 5k + c
whe X=6,Y=4
4 = 6k + c
subtract them
-4 = k
back in 8 = 5k + c
8 = -20 + c
c = 28
so now you have
y = -4x + 28
and finish it off
when X=5,Y=8
8 = 5k + c
whe X=6,Y=4
4 = 6k + c
subtract them
-4 = k
back in 8 = 5k + c
8 = -20 + c
c = 28
so now you have
y = -4x + 28
and finish it off
y = mx+b
The two points give you
5m+b = 8
6m+b = 4
solve for m and b, and then you can easily answer the questions
The two points give you
5m+b = 8
6m+b = 4
solve for m and b, and then you can easily answer the questions