Rational numbers are those that can be put into fraction form. Like .3. It can be put into 3/10. Irrational numbers are those that cannot be put into fraction form. Like pi.
3/7 is rational, A, because it can be written in fraction form, 3/7.
.78 repeating is rational, A, because it can be written in 78/99. Repeating decimals can be written in fraction form.
Square root of 7/9 is irrational because it cannot be written in a simplified form. You can distribute the square root, but the square root of 7 will always be irrational and so the whole number is irrational.
[tex]5 \pi [/tex] is irrational because [tex] \pi [/tex] is irrational and anything multiplied by an irrational is irrational.
