Assist with this problem. it is really difficult.

a) is an identity.

Step-by-step explanation:

Most of the left hand sides are in this form:

.

When you multiply conjugates you do not have to use full foil.  You can just multiply the first and multiply the last or just use this as a formula:

.

Choice a), b), and d). all have the form I mentioned.

So let's look at those choices for now.

a)

 (I used my formula I mentioned above.)

So this is an identity.

b)  

(by use of my formula above)

This is not the right hand side so this equation in b is not an identity.

d)

This is not the same thing as the right hand side so this equation in d is not an identity.

Let's look at c now.

c)

There is a formula for expanding this so that you could avoid foil. It is

.

Just for fun I'm going to use foil though:

First: x^3(x^3)=x^6

Outer: x^3(y^2)=x^3y^2

Inner: y^2(x^3)=x^3y^2

Last: y^2(y^2)=y^4

---------------------------Add.

This is not the same thing as the right hand side.

i dont know

step-by-step explanation:

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0