Counting Combos: 5 T-Shirts & 3 Jeans: 15 Days

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A student has five different t-shirts and three pairs of jeans.

How many days can the student dress without repeating the combination of jeans & t-shirt?
How many days can the student dress without repeating the combination of jeans & t-shirt and without wearing the same t-shirt on two consecutive days?

I think the first question is pretty easy and I got it right... 5x3 = 15 days.

I'm not sure if I'm missing something for the second question, but I'm still getting 15 days. The student could just wear Jeans 1 with Shirts 1-5, then Jeans 2 with Shirts 1-5, and finally Jeans 3 with Shirts 1-5 right?
 
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Abc123Def said:
A student has five different t-shirts and three pairs of jeans.

How many days can the student dress without repeating the combination of jeans & t-shirt?
How many days can the student dress without repeating the combination of jeans & t-shirt and without wearing the same t-shirt on two consecutive days?

I think the first question is pretty easy and I got it right... 5x3 = 15 days.

I'm not sure if I'm missing something for the second question, but I'm still getting 15 days. The student could just wear Jeans 1 with Shirts 1-5, then Jeans 2 with Shirts 1-5, and finally Jeans 3 with Shirts 1-5 right?

I don't see anything wrong with that.
 

Thread 'Prove that the integral is equal to ##\pi^2/8##'

Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
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