HARRY I NEED HELP FAST 15POINTS Which expressions are quadratic expressions? Check all that apply
z^2
2x + 7x - 10
2x^2 + 9x - 7
500(0,25)^t -1
13x^3 + 21x^2-5

First,Third Only

Step-by-step explanation:

Quadratic expression are those expression where the variable has a degree of maximum 2 and only the first and third expression have the degree of 2 in the choices. 2nd choice is a linear expression because both the variables have degree 1. 4th choice has a degree of t which means its an exponential expression, and 5th choice has the degree 2 and 3 but the maximum degree is 3 so it isn't a quadratic is a cubic equation.

Standard form of a quadratic expression

6x+8

Step-by-step explanation:

To answer this question we just simply use the distributive property to get rid of the parenthesis.

1.5*3x=4.5x

1.5*4=6

So the first parenthesis cancelled out would be : 4.5x+6

Now, onto the second:

0.25*6x=1.5x

0.25*8=2  

So the second one is : 1.5x+2

Not that we have distributed both things, we add these.

4.5x+6+1.5x+2 we combine like terms

4.5x+1.5x=6x

6+2=8

So, the answer is 6x+8