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April 21, 2014

April 21, 2014

Posted by **greeny** on Tuesday, February 7, 2012 at 10:29pm.

i got a=3.04 and b= 1.185 so my equation is y=3.04(1.185)^4

is this correct?

one more problem. find a power function of the form y=ax^b whose graph passes through the points (2,3) and (10,21)?

this one im quite confused on how to do, can someone show the steps for it and lead me through until the answer? thanks!

- math -
**Reiny**, Tuesday, February 7, 2012 at 10:52pmI agree with your a and b values, but your equation should have an exponent of x , not 4

(probably just a typo)

2nd:

for (2,3) --> 3 = a(2^b)

for (10,21) ---> 21 = a(10^b)

divide them

21/3 = 10^b/2^b

7 = (10/2)^b

7 = 5^b

take log of both sides

log 7 = log (5^b)

log 7 = b log 5

b = log 7/log 5 = appr. 1.209

sub back into 1st equation

a(2^1.206) = 3

a(2.3119) = 3

a = 1.298

so y = 1.298(x^1.209)

check my arithmetic on the last one

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