a^6b^8-a^4b^3+a^3b^5-a^3b^3 ???

To simplify the given expression "a^6b^8 - a^4b^3 + a^3b^5 - a^3b^3," we can combine like terms by adding or subtracting the coefficients. Notice that each term has a combination of powers of 'a' and 'b.'

Let's break down each term:

1. a^6b^8: This term has the highest powers of both 'a' and 'b,' so it cannot be combined with any other term. It remains unchanged.

2. -a^4b^3: This term has lower powers of 'a' and 'b' compared to the first term. We can combine it with the third term by adding the coefficients of the like terms.

3. +a^3b^5: This term has lower powers of 'a' and higher powers of 'b' compared to the second term. As mentioned earlier, we can combine it with the second term.

4. -a^3b^3: This term has the same powers of 'a' and a lower power of 'b' compared to the second term. We can combine it with the second term.

Combining these terms:

a^6b^8 - a^4b^3 + a^3b^5 - a^3b^3 = a^6b^8 + (-a^4b^3 + a^3b^5 - a^3b^3)

Now, let's simplify the terms with like powers of 'a' and 'b':

= a^6b^8 + (-a^4b^3 - a^3b^3 + a^3b^5)

Next, we can factor out common factors from the coefficients within the parentheses:

= a^6b^8 + (-a^3b^3(a + 1) + a^3b^5)

Now, we have combined as much as possible. The simplified form is:

a^6b^8 - a^3b^3(a + 1) + a^3b^5