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May 29, 2015

May 29, 2015

Posted by **KIRA** on Wednesday, February 20, 2008 at 8:44pm.

Y=23]24]25]26]27

WHAT IS THE VALUE OF Y WHEN X IS 68??

IF Y=X-19, WHAT IS THE VALUE OF X WHEN Y= 34

- MATH -
**Guido**, Wednesday, February 20, 2008 at 8:54pmQuestion 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!

- MATH -
**Damon**, Wednesday, February 20, 2008 at 9:08pmX= 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