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@eric-unc
Created February 12, 2025 03:41
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response2.txt
xbony2@xbony2s-Mac-Pro ~ % ollama run deepseek-r1
>>> What is y if y' = 5x + 2, and y(0) = 0?
<think>
Okay, so I have this problem where I need to find y given that the
derivative of y, which is y', equals 5x plus 2. Also, there's an initial
condition: when x is 0, y is also 0. Hmm, let me try to remember how to
solve differential equations like this.
First off, if y' = 5x + 2, that means the derivative of y with respect to
x is equal to this linear function. To find y, I think I need to
integrate both sides because integration is the reverse process of
differentiation. So, integrating y' should give me y plus a constant.
Alright, let's write that down step by step. If dy/dx = 5x + 2, then to
get y, we integrate (5x + 2) with respect to x. The integral of 5x is...
hmm, the power rule says you increase the exponent by one and divide by
that new number, right? So, integrating 5x would be 5*(x²/2), which
simplifies to (5/2)x².
And then the integral of 2 with respect to x is just 2x. Don't forget,
though, when you integrate, you have to add a constant term because the
derivative of any constant is zero. So, putting it all together, y should
be equal to (5/2)x² + 2x plus some constant C.
But wait, we also have an initial condition: y(0) = 0. That means when x
is 0, y is 0. I can use this information to find the value of C. Let's
plug in those values into our equation.
So, if x is 0, then:
y = (5/2)*(0)^2 + 2*(0) + C
Which simplifies to:
y = 0 + 0 + C
But we know that y(0) = 0, so substituting in:
0 = 0 + C
Therefore, C must be 0.
So now, plugging back the value of C into our equation for y, we get:
y = (5/2)x² + 2x
Let me just double-check my steps to make sure I didn't make any
mistakes. Starting from dy/dx = 5x + 2, integrating gives us y as a
function with terms in x squared and x, plus the constant C. Then
applying the initial condition y(0) = 0 allows us to solve for C, which
turns out to be zero. That seems right.
Wait, another thought: when you integrate 5x, is it indeed (5/2)x²? Yeah, because the integral of x^n is (x^(n+1))/(n+1), so n here is 1 for 5x, making it (5/2)x². Correct. And integrating 2 gives 2x as well.
Just to be thorough, let me take the derivative of our solution y = (5/2)x² + 2x and see if it matches the given y'. So, d/dx [(5/2)x²] is 5x, right? Because the derivative of x squared is 2x, multiplied by 5/2 gives 5x. Then the derivative of 2x is just 2. Adding
them together, we get 5x + 2, which matches y'. Perfect.
And also checking the initial condition: when x=0, plugging into our equation:
y = (5/2)*(0)^2 + 2*(0) = 0 + 0 = 0
Which is exactly what was given. So that checks out as well.
Wait a second, just thinking about if there are any alternative methods or ways to approach this problem? Maybe using substitution or something else? But since it's a straightforward linear differential equation with constant coefficients and an initial condition
at x=0, the method of integrating is the standard approach here. So I think that was the right way.
Is there anything else I might have missed? For example, are we supposed to consider any interval where this solution is valid? Hmm, in this case, since it's a polynomial function and polynomials are defined everywhere on the real line, our solution should be
valid for all x. So no issues with domain or range here.
Another thing: does this represent motion along a straight line or something else? Well, if y is a function of x, then in terms of physics, it's like displacement over time if x represented time. But I don't think we need to interpret it physically unless the
question specifies, which it doesn't. So yeah, our answer should be fine.
So just summarizing:
1. Recognize that y' = 5x + 2 is a differential equation.
2. Integrate both sides with respect to x: ∫(5x + 2) dx
3. Calculate the integral to get (5/2)x² + 2x + C
4. Apply initial condition y(0) = 0 to solve for C, which is 0
5. Substitute back in to find that y = (5/2)x² + 2x
Everything seems consistent and checks out.
**Final Answer**
The value of \( y \) is \boxed{\frac{5}{2}x^2 + 2x}.
</think>
Given the differential equation \( y' = 5x + 2 \) with the initial condition \( y(0) = 0 \), we need to find the function \( y \).
1. Recognize that \( y' = 5x + 2 \) is a differential equation.
2. Integrate both sides with respect to \( x \):
\[
y = \int (5x + 2) \, dx
\]
3. Calculate the integral:
- The integral of \( 5x \) is \( \frac{5}{2}x^2 \).
- The integral of \( 2 \) is \( 2x \).
- Adding the constant of integration \( C \), we get:
\[
y = \frac{5}{2}x^2 + 2x + C
\]
4. Apply the initial condition \( y(0) = 0 \):
- Substitute \( x = 0 \) into the equation:
\[
0 = \frac{5}{2}(0)^2 + 2(0) + C
\]
- Simplifying, we find \( C = 0 \).
5. Substitute \( C = 0 \) back into the equation for \( y \):
\[
y = \frac{5}{2}x^2 + 2x
\]
The value of \( y \) is \boxed{\frac{5}{2}x^2 + 2x}.
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