Engineering
Mathematics
Integration by Substitution

Question

Let  f  and  g  are two linear functions such that

f (x – 1) = 2x – 3 + g(1) – f (1)  and    g(x – 1) = 4x + 5 – g (1) – f (1)   for all real number x.

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Linked Question 1

Area enclosed by the curves  y = f (x),  y = g (x)  and  y = 0, is

12

14

18

1

Solution

No Solution

Linked Question 2

If ∫f(x)+2(f(x)−12)(f(x)+12)(g(x)+74)(g(x)+114)+1 dx=C−1h(x) where h (x) is of the form of ax2 + bx + c,  then (a + b + c) equals

6

5

None

4

Solution

Put  x = 2 in both the equation we get

f (1) = 3  and  g (1) = 5

∴  f (x) = 2x + 1   and     g (x) = 4x + 1

∫2x+3(x2+3x)(x2+3x+2)+1 dx

Put  x2 + 3x = t ⇒ (2x + 3)dx = dt

∫dtt(t+2)+1;

∫dt(t+1)2=C−1t+1=C−1x2+3x+1

⇒ a = 1, b = 3, c = 1

⇒ a + b + c = 5

Linked Question 3

The value of Limx→0  (g(x)f(x))cosecx  is equal to

e4

e3

e2

e

Solution

Put  x = 2 in both the equation we get

f (1) = 3  and  g (1) = 5

∴  f (x) = 2x + 1   and     g (x) = 4x + 1

 Limx→0  (4x+12x+1)cosecx=pq=e2