Posted by KIRA on Wednesday, February 20, 2008 at 8:44pm.
Question 1:
92 - 4 = 88; y = 22
88 - 4 = 84; y = 21
84 - 4 = 80; y = 20
80 - 4 = 76; y = 19
76 - 4 = 72; y = 18
72 - 4 = 68; y = 17
What's the answer?
When x = 68, y = 17.
====================
For question 2:
IF Y = X-19, WHAT IS THE VALUE OF X WHEN Y= 34.
Replace Y with 34 and solve for x.
34 = X - 19
34 + 19 = X
53 = X
Done!
X= 92]96]100]104]108
differences
4, 4, 4, 4
Y=23]24]25]26]27
differences
1, 1, 1, 1
when doing this type of problem, make table of change in x and change in y.
if the ratio of change in y over change in x is constant, we have a straight line.
y = m x + b
If not, make another line, the differences of differences.
if that ratio is constant, you have a parabola.
y = a x^2 + b x + c
etc. That will usually work
Anyway, here we have y = m x + b
put in two points to solve for m and b and you have everything.
we can see from our table that m = change in y / change in x = 1/4
so
y = (1/4) x + b
put in a point (92,23)
23 = (1/4)(92) + b
b = 0 remarkable
SO
y = (1/4) x
so if x = 68, then y = 68/4 = 17