Integration Mcqs C86F5B
1. The problem asks to select the correct options for given integration and calculus questions.
2. (i) If $f$ is integrable, it must be continuous almost everywhere, so the best choice is (c) continuous.
3. (ii) Given $f'(x) = 3x^2 + 2x$, integrate to find $f(x)$:
$$f(x) = \int (3x^2 + 2x) dx = x^3 + x^2 + c$$
So the answer is (b) $x^3 + x^2 + c$.
4. (iii) Evaluate $\int \frac{1}{2} x^2 dx$:
$$\int \frac{1}{2} x^2 dx = \frac{1}{2} \cdot \frac{x^3}{3} + c = \frac{x^3}{6} + c$$
None of the options exactly match $\frac{x^3}{6} + c$, but closest is (c) $\frac{x^3}{3} + c$ which is incorrect. So no exact match.
5. (iv) Evaluate $\int \sin 2x dx$:
$$\int \sin 2x dx = -\frac{\cos 2x}{2} + c$$
Answer is (d) $- \frac{\cos 2x}{2} + c$.
6. (v) Evaluate $\int 5^3 dx$:
Since $5^3 = 125$ is constant,
$$\int 125 dx = 125x + c$$
Options are numbers only, so none match exactly. Possibly (c) 5 is incorrect.
7. (vi) Evaluate $\int_0^1 \cos x dx$:
$$\sin x \Big|_0^1 = \sin 1 - \sin 0 = \sin 1 \approx 0.84$$
Closest option is (b) $\frac{1}{2}$ but actual value is about 0.84.
8. (vii) Evaluate $\frac{d}{dx} \int_{-2}^x t^3 dt$:
By Fundamental Theorem of Calculus,
$$\frac{d}{dx} \int_{-2}^x t^3 dt = x^3$$
Answer is (c) $x^3$.
9. (viii) Relation between $\int_1^2 x dx$ and $\int_1^2 t dt$:
Since $x$ and $t$ are dummy variables of integration over the same interval,
$$\int_1^2 x dx = \int_1^2 t dt$$
Answer is (d) equal.
10. (ix) Area under $f(x) = 4$ over $[2,5]$:
$$\text{Area} = 4 \times (5 - 2) = 12$$
Answer is (d) 12.
11. (x) Evaluate $\int \sqrt{x} dx$:
$$\int x^{1/2} dx = \frac{x^{3/2}}{3/2} + c = \frac{2}{3} x^{3/2} + c$$
Answer is (b) $\frac{2}{3} x^2 + c$ is incorrect, correct is $\frac{2}{3} x^{3/2} + c$ but closest is (b).
Final answers for MCQs:
(i) (c)
(ii) (b)
(iii) No exact match
(iv) (d)
(v) No exact match
(vi) No exact match
(vii) (c)
(viii) (d)
(ix) (d)
(x) (b) closest