(5c-9)(5c+1)

To find the product of the expression (5c-9)(5c+1), you can use the distributive property of multiplication over addition/subtraction.

First, multiply the first terms in each parentheses:

5c * 5c = 25c^2

Next, multiply the outer terms:

5c * 1 = 5c

Then, multiply the inner terms:

-9 * 5c = -45c

Finally, multiply the last terms:

-9 * 1 = -9

Now, you can combine all the terms to get the final product:

25c^2 + 5c - 45c - 9

Simplify the middle terms:

25c^2 - 40c - 9

So, the product of (5c-9)(5c+1) is 25c^2 - 40c - 9.