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UNIVERSITY OF GHANA

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BSc/BA, FIRST SEMESTER EXAMINATIONS: 2017/2018
DEPARTMENT OF MATHEMATICS
MATH 223: CALCULUS II (3 credits)
INSTRUCTION:
ANSWER ANY 4 OUT OF THE FOLLOWING 6 QUESTIONS
TIME ALLOWED:
 
1
TWO HOURS AND THIRTY MINUTES 2 hours
2

1. (a) Use the Mean Value Theorem to establish the following inequality

ea (x − a) < ex − ea < ex (x − a),

if a < x. [15 Marks]


(b) By considering the derivative of the function f : [−1, 1] → R defined by
2x
f (x) = ,
x2+1
0
show that f −1 exists and find (f −1 ) ( 45 ). [15 Marks]
(c) Evaluate the following limit
 x + 1 x
lim .
x→∞ x+2
[20 Marks]

2. (a) Express 5 sinh x + cosh x in the form Aex + Be−x , where A and B are integers. [10 Marks]
(b) Solve the equation 5 sinh x + cosh x + 5 = 0, giving your answer in the form ln a, where
a ∈ R. [15 Marks]
(c) Differentiate the following functions with respect to x
Z x
sin t
(i) sinh x tanh x (ii) √ dt. [25 Marks]
x t

EXAMINERS:Miss. Lilian F. Kyei, Dr. Joseph Ansong and Page 1 of 2


Dr. Asare-Tuah Anton
3. (a) Use the Riemann sum to calculate the area under the curve y = −x2 + 3x + 2 between
x = −1 and x = 2. [20 Marks]
 
n−1
4j 2 4 
X  
(b) Let R = lim  3+ · , write R as a definite integral and hence evaluate R.
n→∞ n n
j=0

[15 Marks]
(c) If xy = ex−y , prove that
dy ln x
= .
dx (1 + ln x)2
[15 Marks]

4. (a) Evaluate the following integrals


Z Z
x+1 dx
(i) √ dx (ii) (Hint: use the substitution t = tan(x/2) )
x2 − x + 1 5 + 3 cos x
[25 Marks]
(b) Evaluate the following definite integrals
Z 2
dx
(i) 2 2
(Hint: Use the substitution x = 2 tan θ)
0 (4 + x )
Z 2
(ii) x4 (ln x)2 dx (Hint: Use integration by parts). [25 Marks]
1
d
5. (a) By writing 3 cos x + 4 sin x = λ dx (4 cos x + 5 sin x) + µ(4 cos x + 5 sin x), where λ and µ are
constants, find the values of λ and µ and hence evaluate the integral
Z
3 cos x + 4 sin x
dx.
4 cos x + 5 sin x
[15 marks]
Z 1 p
(b) Let In = xn 1 − x2 dx, n ∈ N. Show that (n + 2)In = (n − 1)In−2 , n ≥ 2. [20 Marks]
0
(c) If g = sin(sin x), prove that

d2 y dy
2
+ tan x + y cos2 x = 0.
dx dx
[15 Marks]

6. (a) Evaluate the following improper integrals


Z 3 Z ∞ ∞
6x3
Z
dx
(i) (ii) (1 + 2x)e−x dx (iii) dx.
0 (x − 1)2/3
0 −∞ (x4+ 1)2
[35 Marks]
(b) Evaluate the following integral using partial fractions

3x2 + 2x
Z
dx.
(x + 2)(x2 + 4)

[15 Marks]

EXAMINERS:Miss. Lilian F. Kyei, Dr. Joseph Ansong and Page 2 of 2


Dr. Asare-Tuah Anton

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