One can show that the union of two countable sets is countable. Is the set of irrational real numbers countable?

Find the volume V of the described solid S
A cap of a sphere with radius r and height h.
V=??

Whether each of these functions is a bijection from R to R.

a) $f(x)=-3x+4$

b) ${\displaystyle f\left(x\right)=-3x^2+7}$

c) $f(x)=\frac{x+1}{x+2}$
${\displaystyle d)f\left(x\right)=x^5+1}$

In how many different orders can five runners finish a race if no ties are allowed???

State which of the following are linear functions?
a. $f(x)=3$
b. $g(x)=5-2x$
c. ${\displaystyle h\left(x\right)=\frac{2}{x}+3}$
d. $t(x)=5(x-2)$

Three ounces of cinnamon costs $2.40. If there are 16 ounces in 1 pound, how much does cinnamon cost per pound?

A square is also a
A)Rhombus;
B)Parallelogram;
C)Kite;
D)none of these

What is the order of the numbers from least to greatest.
${\displaystyle A=1.5\times {10}^3}$,
${\displaystyle B=1.4\times {10}^{-1}}$,
${\displaystyle C=2\times {10}^3}$,
${\displaystyle D=1.4\times {10}^{-2}}$

Write the numerical value of ${\displaystyle 1.75\times {10}^{-3}}$

Solve for y. 2y - 3 = 9
A)5;
B)4;
C)6;
D)3

How to graph ${\displaystyle y=\frac{1}{2}x-1}$?

How to graph ${\displaystyle y=2x+1}$ using a table?

simplify ${\displaystyle \sqrt{257}}$

How to find the vertex of the parabola by completing the square ${\displaystyle x^2-6x+8=y}$?

There are 60 minutes in an hour. How many minutes are there in a day (24 hours)?

Write 18 thousand in scientific notation.