Which of the following must be true for an expression to be a difference of two squares?

a. all variables are raised to an even power
b. there are only two terms
c. both terms have negative coefficients

a. a, b, and c
b. b and c
c. a and b
d. a and c

C is the correct option.

Step-by-step explanation:

The true statements are :

a. all variables are raised to an even power

b. there are only two terms.

Here, we will take the example of:

This equation consists of two perfect squares, and . The variables are raised to even power (2) and also the equation has 2 terms.

Upon factoring we get .

Therefore, we can say that the difference of two squares means that both terms of the equation should be square numbers. This is not possible for more than 2 terms.

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!