Question

can someone help me learn expressions? (algebra 1)

Answer 1

can you give an example for me to help you with

Answer 2

Yes, please be specific about what you want to know. "Expressions" is a very wide topic.

Go to your homework assignment and choose a couple of expressions to discuss. What do they have in common? What makes them "expressions?"

Answer 3

i dont have an assignment.. its for a state test and I really need to refresh on this.

Answer 4

i guess 2x + 3 would be an example

Answer 5

do you know what makes an expression different than an equation?

Answer 6

no

Answer 7

that's a good place to start!

an "expression" is group of numbers, symbols (like variables), and operators (things like + - , multiplication, division,etc)

Answer 8

an "equation" is two or more expressions that are set equal to each other

ex: 2x + 3 = y

Answer 9

make sense?

Answer 10

ahh okay! i understand

Answer 11

is there anything that you'd like to talk about, regarding expressions? anything unclear or confusing?

Answer 12

have you worked with variables (letters) before?

Answer 13

like how to solve one maybe?

Answer 14

sure!

Answer 15

usually, when we solve an equation, there is some unknown number we want to know

Answer 16

we can call it a variable like "x" until we figure out what it is

Answer 17

is this for expression or equation?

Answer 18

equation

Answer 19

you can't "solve" an expression

Answer 20

what happens when i get an expression on the test? what do i do?

Answer 21

they'll ask you to do something with it

Answer 22

can you give an example?

Answer 23

like, they won't just say

"2x + 3"

and then nothing else

Answer 24

they might ask you to create an expression for a real-life situation

Answer 25

i found one..

valuate the following expression when x= 2 and y= -3.
5x -7y

Answer 26

oh ok that's good!

Answer 27

x= 2 and y= -3

mean that you can replace "x" with "2" and "y" with "-3"

with me so far?

Answer 28

yes

Answer 29

now, our expression is:

5x -7y

let's replace "x" with "2" and "y" with "-3"

Answer 30

5x -7y

turns into:

5(2) - 7(-3)

which is a simple math problem

Answer 31

5x means "5 times x" and "7y" means "7 times y"

Answer 32

ok so it would be 10 - -21

Answer 33

good! and that equals 31

Answer 34

okay :) thats all there is to expressions?

Answer 35

yeah, pretty much

Answer 36

ok do you think you can help with equations now?

Answer 37

oh wait

Answer 38

do you know how to simplify something like:

5x + 3x - 2y + 3y?

Answer 39

no

Answer 40

when we "simplify" something, we want to write it in the shortest, least complex way possible

Answer 41

Medals 1
so, if somebody asked you to add 2 + 1 + 4 + 6, you would say "13" and not something like "7 + 6" or "10 + 3" even though they're equal

Answer 42

make sense so far?

Answer 43

yes

Answer 44

so, going back to our expression

5x + 3x - 2y + 3y

we can write this in a shorter way

Answer 45

do you know how to add 5x + 3x?

Answer 46

8x ?

Answer 47

good!

Answer 48

what about -2y + 3y?

Answer 49

no im not sure

Answer 50

hint: what is -2 + 3?

Answer 51

1y ?

Answer 52

good

special rule: when we have the number "1" in front of a variable, we don't write it

so 1y is actually written as "y"

make sense?

Answer 53

ahh okay!

Answer 54

just remember: in order to add/subtract/multiply/divide/ etc. things with variables, they have to be the same variable

Answer 55

for example: you can add 5x + 3x to get 8x, but you cannot add 3x + 5y to get anything else

Answer 56

how would you solve if there was different variables like that?

Answer 57

if they ask you to simplify an expression with different variables, you would stop when you get to that point

Answer 58

going back to our example:

Answer 59

5x + 3x - 2y + 3y

we stopped when we got to 8x - y

Answer 60

*** 8x + y

Answer 61

ahh okay but what if like 5x + 3y - 2x + 3y

would you just add 5x and 2x

and then 3y and the other 3y ?

Answer 62

yes, good job! your final answer would be 3x + 6y

Answer 63

ahh okay! i got it! :)

Answer 64

only one last thing I can think of: this is a very common mistake people make

ex:
5x + 7

does NOT equal 12 OR 12x.

Answer 65

5 + 7 = 12
5x + 7x = 12x

but 5x + 7 cannot be simplified further since the 5 has the x attached to it, and the 7 doesn't

Answer 66

ahh okay what would the answer be for something like that?

Answer 67

like with the previous example, you would stop when you get to that point

Answer 68

ex:

can you try simplifying

3x + 4 - x + 3?

Answer 69

3x + 7 ??

Answer 70

almost!

Answer 71

what is 3x - x?

Answer 72

3?

Answer 73

not quite! hint: you can pretend there is an imaginary "1" in front of the x

Answer 74

3x - 1x = ?

Answer 75

2x?

Answer 76

good!

Answer 77

okay that makes sense!

Answer 78

3x + 4 - x + 3 = 2x + 7 which would be the final answer

Answer 79

that's all I can think of, but feel free to ask me or any of us if you have any specific questions

Answer 80

okay! thank you soo much! im gonna go write all of this down so i can remember. but thank you this reallly does help me!

Answer 81

np, good luck on your test