Ali Hey Jamshed, are you ready for the final exam in math?
Jamshed I'm not sure, Ali. I’ve been trying to study, but I still have some doubts. Can we go over a few problems together?
Ali Of course! What topics do you need help with?
Jamshed I’m struggling with calculus, specifically integration and differential equations. Also, some trigonometry concepts are still a bit fuzzy.
Ali No problem. Let’s start with integration. Do you have any specific problems you’re stuck on?
Jamshed: Yeah, there’s this one: \(\int (3x^2 - 4x + 5) \, dx\). I’m not sure how to approach it.
Ali: That’s a basic polynomial integration. You integrate each term separately. For \(3x^2\), you use the power rule which says \(\int x^n \, dx = \frac{x^{n+1}}{n+1}\). So,
\[
\int 3x^2 \, dx = 3 \cdot \frac{x^3}{3} = x^3
\]
For \(-4x\), it’s similar:
\[
\int -4x \, dx = -4 \cdot \frac{x^2}{2} = -2x^2
\]
And for the constant \(5\),
\[
\int 5 \, dx = 5x
\]
Putting it all together,
\[
\int (3x^2 - 4x + 5) \, dx = x^3 - 2x^2 + 5x + C
\]
where \(C\) is the constant of integration.
Jamshed: That makes sense! Thanks, Ali. What about differential equations?
Ali: Sure, let’s tackle one. How about this: Solve \(\frac{dy}{dx} = 3x^2\).
Jamshed: Okay, so I need to find \(y\) in terms of \(x\), right?
Ali: Exactly. This is a straightforward first-order differential equation. You just integrate both sides. So,
\[
\int \frac{dy}{dx} \, dx = \int 3x^2 \, dx
\]
This simplifies to:
\[
y = \int 3x^2 \, dx = x^3 + C
\]
Jamshed: Got it! That’s pretty similar to the integration problem. Thanks, Ali. Now, what about trigonometry? I get confused with the identities.
Ali: Trig identities can be tricky. Let’s go over a common one: the Pythagorean identity. Do you remember it?
Jamshed: Umm, is it \(\sin^2 x + \cos^2 x = 1\)?
Ali: Yes, that’s correct! And it’s very useful. For example, if you know \(\sin x\), you can find \(\cos x\). Let’s try a problem: If \(\sin x = \frac{3}{5}\), find \(\cos x\).
Jamshed: Alright, using \(\sin^2 x + \cos^2 x = 1\):
\[
\left(\frac{3}{5}\right)^2 + \cos^2 x = 1
\]
That gives:
\[
\frac{9}{25} + \cos^2 x = 1
\]
So,
\[
\cos^2 x = 1 - \frac{9}{25} = \frac{16}{25}
\]
Therefore,
\[
\cos x = \pm \frac{4}{5}
\]
Ali Perfect! Remember, \(\cos x\) can be positive or negative depending on the quadrant.
Jamshed:Thanks, Ali. This really helped clarify things. I feel more confident now!
Ali: Glad I could help, Jamshed. Good luck with the exam!
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