CBSE 12th Standard Maths Subject Integrals Ncert Exemplar 4 Mark Questions With Solution 2021
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CBSE 12th Standard Maths Subject Integrals Ncert Exemplar 4 Mark Questions With Solution 2021
12th Standard CBSE
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Reg.No. :
Maths
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Evaluate the integral: \(\int {x^3\over x^4+3x^2+2}dx.\)
(a) -
Evaluate the integral: \(\int{x^2\over x^4+x^2-2}dx\)
(a) -
Evaluate the integral: \(\int {sin^6\ x+cos^6\ x\over sin^2\ x\ cos^2\ x}dx\)
(a) -
Evaluate the integral: \({\sqrt x\over \sqrt{a^3-x^3}}dx\)
(a) -
Evaluate the following integral
\(\int \frac{x+5}{3 x^{2}+13 x-10} d x\)(a) -
Evaluate the following integral.
\(\int \frac{x^{3}}{x^{4}+3 x^{2}+2} d x\)(a) -
Evaluate the following integral.
\(\int \frac{(2 x-1)}{(x-1)(x+2)(x-3)} d x\)(a) -
Evaluate the following as limit of sum
\(\int_{-1}^{2}(7 x-5) d x\)(a) -
Evaluate the following integral.
\(\int_{0}^{1} x\left(\tan ^{-1} x\right)^{2} d x\)(a) -
Evaluate the following integral.
\(\int_{\pi / 3}^{\pi / 2} \frac{\sqrt{1+\cos x}}{(1-\cos x)^{5 / 2}} d x\)(a)
4 Marks
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CBSE 12th Standard Maths Subject Integrals Ncert Exemplar 4 Mark Questions With Solution 2021 Answer Keys
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\(log\ |{x^2+2\over\sqrt{x^2+1}}|+c\)
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\({2\over 3\sqrt2}tan^{-1}{x\over\sqrt2}+{1\over 6}log|{x-1\over x+1}|+c\)
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\(tan\ x-cot\ x-3x+c\)
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\({2\over3}sin^{-1}\sqrt{x^3\over a^3}+c\)
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Let \(I=\int \frac{(x+5)}{3 x^{2}+13 x-10} d x\)
\(=\int \frac{(x+5)}{(x+5)(3 x-2)} d x \)
\(=\int \frac{d x}{3 x-2}=\frac{1}{3} \log |3 x-2|+C \) -
Write the given integral as \(\int \frac{x^{2} \cdot x}{\left(x^{2}\right)^{2}+3 x^{2}+2} d x\)
Put \(x^{2}=t\) then above integral reduces to
\(\frac{1}{2} \int \frac{t}{t^{2}+3 t+2} d t\)
\(\log \left|\frac{x^{2}+2}{\sqrt{x^{2}+1}}\right|+C\) -
\(\frac{2 x-1}{(x-1)(x+2)(x-3)}=\frac{A}{x-1}+\frac{B}{x+2}+\frac{C}{x-3}\)
\(\log \left|\frac{\sqrt{x-3}}{(x-1)^{1 / 6}(x+2)^{1 / 3}}\right|+C\) -
\(\frac{-9}{2}\)
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Let \(I=\int_{0}^{1} x\left(\tan ^{-1} x\right)^{2} d x\)
Now, put \(x=\tan \theta \Rightarrow d x=\sec ^{2} \theta d \theta\)
Upper limit When \(x=1, \tan \theta=1 \Rightarrow \theta=\tan ^{-1}(1)=\frac{\pi}{4}\)
Lower limit When \(x=0, \tan \theta=0 \Rightarrow \theta=\tan ^{-1}(0)=0\)
Now, from Eq. (i), we have
\(I=\int_{0}^{\pi / 4} \tan \theta \cdot \theta^{2} \cdot \sec ^{2} \theta d \theta=\int_{0}^{\pi / 4} \theta_{1}^{2}\left(\tan \theta \cdot \sec ^{2} \theta\right) d \theta\)
\(=\left[\theta^{2} \cdot \frac{\tan ^{2} \theta}{2}\right]^{\pi / 4}-\int_{0}^{\pi / 4} 2 \theta \cdot \frac{\tan ^{2} \theta}{2} d \theta\)
\(\left[\because \int \tan x \sec ^{2} x d x=\frac{\tan ^{2} x}{2}\right]\)
\( =\frac{1}{2}\left[\frac{\pi^{2}}{16}\left(\tan \frac{\pi}{4}\right)^{2}-0\right]-\int_{0}^{\pi / 4} \theta \cdot\left(\sec ^{2} \theta-1\right) d \theta\ {\left[\because \sec ^{2} \theta-\tan ^{2} \theta=1\right]} \)
\(\begin{array}{r} =\frac{1}{2}\left[\frac{\pi^{2}}{16}\left(\tan \frac{\pi}{4}\right)^{2}-0\right]-\int_{0}^{\pi / 4} \theta \cdot\left(\sec ^{2} \theta-1\right) d \theta\ {\left[\because \sec ^{2} \theta-\tan ^{2} \theta=1\right]} \end{array}\)
\(=\frac{\pi^{2}}{32}-\left[\theta \cdot(\tan \theta-\theta)-\int 1 \cdot(\tan \theta-\theta) d \theta\right]_{0}^{\pi / 4}\)
\(=\frac{\pi^{2}}{32}-\left[\theta \cdot \tan \theta-\theta^{2}\right]_{0}^{\pi / 4}+\int_{0}^{\pi / 4}(\tan \theta-\theta) d \theta\)
\(=\frac{\pi^{2}}{32}-\left[\frac{\pi}{4} \tan \frac{\pi}{4}-\frac{\pi^{2}}{16}-0\right]+\left[\log |\sec \theta|-\frac{\theta^{2}}{2}\right]_{0}^{\pi / 4}\)
\(=\frac{\pi^{2}}{32}-\frac{\pi}{4}+\frac{\pi^{2}}{16}+\log \sqrt{2}-\frac{\pi^{2}}{32}-0 \quad\left[\because \tan \left(\frac{\pi}{4}\right)=1\right]\)
\(=\frac{\pi^{2}-4 \pi}{16}+\log \sqrt{2}\) -
Let \(I=\int_{\pi / 3}^{\pi / 2} \frac{\sqrt{1+\cos x} d x}{(1-\cos x)^{5 / 2}}=\int_{\pi / 3}^{\pi / 2} \frac{\sqrt{1-\cos ^{2} x}}{(1-\cos x)^{\frac{5}{2}+\frac{1}{2}}} d x\)
[multiplying numerator and denominator by \(\sqrt{1-\cos x}\) ]
\(=\int_{\pi / 3}^{\pi / 2} \frac{\sin x}{(1-\cos x)^{3}} d x\)
(ii) Put 1 - cos x = t and simplify it. = \(\frac{3}{2}\)
4 Marks