One value of ∫ f'(x) dx is
As (∫f'(x)dx) = f(x) + C, therefore, one value of (∫ f'(x) dx) is f(x)
∫ log x dx is equal to
ANSWER :- a
Solution :- Let e^x/2 = tanθ. Then 1/2e^(x/2)dx = sec^2θdθ.
∫dx/(e^x+1) = 2∫½ e^(x/2)dx/[e^(x/2)(e^x+1)]
= 2∫[sec^2θdθ]/tanθ(sec^2θ)
= 2∫cosθ/sinθ)dθ = 2ln |sinθ|
From tanθ = e^(x/2) draw a right triangle to see that sinθ = e^x/2√e^x+1:
= 2ln∣e^pi/2√(e^x + 1)|
= ln |e^x/(e^x+1)|
= x−ln(e^x+1)+ C
if ∫ g(x) dx = g(x), then is equal to
If f (x) be a function such that
∫ log xdx = xlog x - x = x(log x -1)
= x(log x - log e) =
Dividing numerator and denominator by cos2x and substituting tanx = t , we get :
∫ sec2 x cosec2 x dx is equal to
Note that sin9x is an odd function, therefore,
∫ log(1-x) dx - ∫ log x dx = 0
∫ (tan x + cot x) dx is equal to
Correct Answer :- c
Explanation : ∫(tanx + cotx)dx
= ∫tanxdx + ∫cotxdx
= ∫sinx/cosx dx + ∫cosx/sinx dx
I1 = sinx/cosx
Put t = cosx
dt = -sinx dx
I2 = cosx/sinx
Put t = sinx
dt = cosx dx
So, we get
=> ∫-dt/t + ∫dt/t
=> - ln t + ln t + c
=> -ln cosx + ln sinx + c
=> log (sinx/cosx) + c
=> log(tanx)
∫ log(log x) + (log x)-1) dx is equal to
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