I mean, sure, it's an arguable position, but an actively unhelpful use of language. You're arguing that anybody that knows about gradients (or even just like, how two still objects don't move) knows calculus, therefore most people must know calculus by like age 8.
You're not employing the tools of calculus in any meaningful or non-negligible way. You're just using basic newtonian laws and claiming you used complex quantum mechanics waveforms. Show your actual working out of the derivative just like you did with the basic algebra and I'll concede and give you the star sticker.
The gradient of any line is mx + c = y, that's grade school math. That's all you used to work it out and you're claiming you used calculus.
Alas, the answer for the coveted star was:
Multiply the equation with d/dt: (d/dt) * t*sqrt(26) = dt * sqrt(26) / dt.
dts cancel out, therefore the derivative is sqrt(26).
Still a very unnecessary (and simple) application of calculus, but at least it would've shown that's whatcha did.