add 5y-4 and 2y^2-8y

my answer is: 2y^2-3y-4

classify the following, if possible
7x^2+10xy+y^2

a)not classified
b)trinomial
c)monomial
d)binomial
My answer: trinomial

Write using positive exponents, and simplify if possible

(-3x)^-2

a)(1)/(6x^2)
b)(9)/(x^2)
c)(1)/(9x^2)
d) - (9)/(x^2)

My answer: d

all correct, except the last. The 3 is in the () that has an exponent.

To add the expressions 5y - 4 and 2y^2 - 8y, you simply combine like terms.

Step 1: Add the coefficients of the y terms. 5y - 8y = -3y.
Step 2: Combine the constants. -4 + 0 = -4.

Putting it all together, the sum of the two expressions is -3y - 4, which matches your answer of 2y^2 - 3y - 4.

To classify the expression 7x^2 + 10xy + y^2, we need to determine the number of terms it has. In this case, we have three terms: 7x^2, 10xy, and y^2.

Based on the number of terms, the expression is classified as a trinomial. Therefore, your answer of "trinomial" is correct.

Now, let's simplify the expression (-3x)^-2 and write it using positive exponents when possible. We can simplify negative exponents by moving them to the denominator or flipping the base.

Step 1: Apply the negative exponent to the base. (-3x)^-2 becomes 1/(-3x)^2.
Step 2: Simplify the expression in the denominator. (-3x)^2 = 9x^2.

Putting it all together, the simplified expression is 1/(9x^2). Therefore, your answer choice of c) (1)/(9x^2) is correct.

In summary:
- The sum of 5y - 4 and 2y^2 - 8y is -3y - 4.
- The expression 7x^2 + 10xy + y^2 is classified as a trinomial.
- The expression (-3x)^-2 simplifies to 1/(9x^2).