Area Question 26

Question 26

  1. The area bounded by the curves y=f(x), the X-axis and the ordinates x=1 and x=b is (b1)sin(3b+4). Then, f(x) is equal to

(1982,2M)

(a) (x1)cos(3x+4)

(b) 8sin(3x+4)

(c) sin(3x+4)+3(x1)cos(3x+4)

(d) None of the above

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Solution:

  1. Since, 1bf(x)dx=(b1)sin(3b+4)

On differentiating both sides w.r.t. b, we get

f(b)=3(b1)cos(3b+4)+sin(3b+4)

f(x)=sin(3x+4)+3(x1)cos(3x+4)



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