1. which expression is equivalent to 2x+3y+4x
a. 9xy b. 18xy c. 5x+3y d. 6x+3y
2. which expression is equivalent to 4(2x-3)
a. 2x-12 b. 6x+1 c. 8x-3 d. 8x-12

Question 1 Which expression is equivalent to 2x+3y+4x?

Here we have three numbers being multiplied by a variable.
We can simplify the expression here...but how is it done?
Well, the variable works sort of like a unit here...say we had
2 apples + 3 oranges + 4 apples.
We would then simplify to
6 apples + 3 oranges.

Variables are combined in the same way...you can only do it if you have the same variables. This is called combining like terms.



Question 2 Which expression is equivalent to 4(2x-3)?

Here, we use what is called the distributive property.
Say we had 4 baskets, each with 2 apples and 3 oranges.
We can conclude that there are 4×2 apples and 4×3 oranges.
You multiply to both terms inside the parentheses!

the formula of a slope:

we have the points (-2, 7) and (2, 3). substitute:

answer: the slope is equal -1.