Posted by **Jay** on Friday, December 2, 2011 at 3:55pm.

Can someone help me with these questions?

1.What are the maximum and minimum values for Y=28(1.21)^x on the interval 0<x<12?

a) 275.8 and 0

b) 275.8 and 28

c) 249.7 and 28

d) 188.4 and 28

2. For what value of x does the maximum or minimum of f(x)= x^2 +8x + 12 occur? Is the point a maximum or minimum?

a) -2; maximum

b) -6; maximum

c) -4; minimum

d) 4; minimum

3. The monthly revenue for printer ink for a large office supply store is R(x) = -x^2 + 12x + 13, where x is the price of an ink cartidge in dollars and R(x) is in hundreds of dollars. What is the maximum monthly ink revenue?

a)$49

b)$3600

c)$4900

d)%12, 100

Thank you~ help needed pls T.T

- Math -
**Steve**, Friday, December 2, 2011 at 4:41pm
since n^0 = 1 for any nonzero n,

28(1.21^x) on 0 < x < 12 goes from

28(1) to 28(9.849) = 28 to 275.77

so (B)

______________________

since the x^2 term has a positive coefficient, the parabola open upward, meaning it has a minimum

This minimum occurs when x = -b/2a = -8/2 = -4

so, (C)

______________________

max occurs when x = -b/2a = -12/2 = 6

R(6) = -36 + 72 + 13 = 49

so (C)

- Math -
**Jay**, Saturday, December 3, 2011 at 12:45am
is it $49 or 4900? you said R(6) = -36 + 72 + 13 = 49

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