Write as a polynomial (a+2b)(4a–5b)–(3a–b)(b–a)

7a^2-ab-9b^2

Step-by-step explanation:

Let's do this in two steps. First, we multiply the first two parentheses:

(a+2b)(4a-5b)

4a^2-5ab+8ab-10b^2 = 4a^2+3ab-10b^2

Then, do the other two parentheses:

(3a-b)(b-a)

3ab-3a^2-b^2+ab = 4ab-3a^2-b^2

Then, combine them:

4a^2+3ab-10b^2-4ab+3a^2+b^2 = 7a^2-ab-9b^2

arrange the equations with like terms in columns.

analyze the coefficients of x or y.

add the equations and solve for the remaining variable.

substitute the value into either equation and solve.

check the solution.

step-by-step explanation: