Math 1425.P70 Examples for 3.5 & 3.6 Name 1)

Math 1425.P70
Examples for 3.5 & 3.6
Name _______________________________________________
Differentiate.
1) y = 6 x
2) f(x) = 210x
3) y = 1011x
4) y = 21-x
5) y = log5 x
6) f(x) = 2 log x
7) f(x) = log
x
5
8) y = log(5x)
9) y = log5 (9x)
Examples for 3.5 & 3.6
10) f(x) = x5 log7 x
11) f(x) = log7(x5 + 1)
12) f(x) = ex log4 x
Solve the problem.
13) In one city, 29% of all aluminum cans distributed will be recycled each year. A juice company distributes
161,000 cans. The number still in use after time t, in years, is given by
N(t) = 161,000(0.29)t.
Find N'(t).
14) The magnitude R (measured on the Richter scale) of an earthquake of intensity I is defined as
R = log
I
.
I0
where I0 is a minimum intensity used for comparison. What is the magnitude on the Richter scale of an
earthquake whose intensity, I, is 104 I0 ?
15) The intensity I of an earthquake is given by
I = I0 10R,
where R = the magnitude on the Richter scale, I0 is the minimum intensity, and R = 0 is used for comparison.
Find I, in terms of I0 , for an earthquake of magnitude 4 on the Richter scale.
Math 1425.P70 Examples for 3.5 & 3.6, page 2
16) The pH scale is used by chemists to measure the acidity of a solution. It is a base 10 logarithmic scale. The pH,
P, of a solution is defined as
P = - log10H,
dP
where H = [H3 O+ ] is the hydronium ion concentration in moles per liter. Find the rate of change
.
dH
Differentiate.
17) f(x) = 4 5x
18) f(x) = 3 x7
19) y = 8xx2
20) y = (x + 1)x
Math 1425.P70 Examples for 3.5 & 3.6, page 3
Find the elasticity.
21) q = D(x) = 500 - x
22) q = D(x) = 400 - 2x
23) q = D(x) =
1200
x
24) q = D(x) = 300 - x
25) q = D(x) = 700e-0.26x
For the demand function given, find the elasticity at the given price and state whether the demand is elastic, inelastic, or
whether it has unit elasticity.
26) q = D(x) = 600 - x; x = 91
27) q = D(x) = 300 - 4x; x = 65
28) q = D(x) =
1500
; x = 49
x
29) q = D(x) = 600 - x; x = 560
Math 1425.P70 Examples for 3.5 & 3.6, page 4
Answer Key
Testname: 1425_SECTION3_5__3_6
1) (ln 6)6 x
2) (ln 210)210x
3) 11 ∙ (ln 10) ∙ 1011x
4) (-ln 21)21-x
5)
1
x(ln 5)
6)
2
x(ln 10)
7)
1
x(ln 10)
8)
1
x(ln 10)
9)
1
x(ln 5)
10)
x4
+ 5x4 (log7 x)
ln 7
11)
5x4
(ln 7)(x5 + 1)
12) ex
1
+ log4 x
x(ln 4)
13) N'(t) = 161,000(ln 0.29)(0.29)t
14) 4
15) 10,000 I0
16)
dP
1
=dH
Hln 10
17) (5ln 4 )4 5x
18) 7ln 3(x 6 ) 3 x7
19) 8xx 2 (2x ln 8x +x)
20) (x + 1)x ln(x + 1) +
21) E(x) =
x
500 - x
22) E(x) =
x
200 - x
x
x+1
23) E(x) = 1
24) E(x) =
x
600 - 2x
25) E(x) = 0.26x
91
26)
; inelastic
509
27)
13
; elastic
2
28) 1; unit elasticity
29) 7; elastic
Math 1425.P70 Examples for 3.5 & 3.6, page 5