2.2 Set Operations: Discrete Mathematics and its application

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Ex 36, p 147.

Let f be a function from the set A to the Set B. Let S and T be the subset of A. Show that

b) f(S \cap T) \subseteq f(S) \cap f(T).

Thanks.
 
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Any time you prove subset relations, you have to show that any element of the subset is an element of the parent set. Let x be an element of the subset, show it is in the parent set.
 
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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