To add these radicals together their radicands must be the same:

9\( \sqrt{28} \) + 5\( \sqrt{7} \)
9\( \sqrt{4 \times 7} \) + 5\( \sqrt{7} \)
9\( \sqrt{2^2 \times 7} \) + 5\( \sqrt{7} \)
(9)(2)\( \sqrt{7} \) + 5\( \sqrt{7} \)
18\( \sqrt{7} \) + 5\( \sqrt{7} \)

Now that the radicands are identical, you can add them together:

A factorial has the form n! and is the product of the integer (n) and all the positive integers below it. For example, 5! = 5 x 4 x 3 x 2 x 1 = 120.

To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so subtract the coefficients and retain the base and exponent:

7b³ - 6b³
(7 - 6)b³
b³

To divide fractions, invert the second fraction and then multiply:

\( \frac{4}{8} \) ÷ \( \frac{1}{7} \) = \( \frac{4}{8} \) x \( \frac{7}{1} \)

To multiply fractions, multiply the numerators together and then multiply the denominators together:

\( \frac{4}{8} \) x \( \frac{7}{1} \) = \( \frac{4 x 7}{8 x 1} \) = \( \frac{28}{8} \) = 3\(\frac{1}{2}\)

To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so add the coefficients and retain the base and exponent:

4a⁴ + 8a⁴
(4 + 8)a⁴
12a⁴