graph the equation by plotting three points -3x+2y=2
can you change it to y = mx+b form ? the first step is add+3x to both sides
0x+5y=5
no. just write +3x to both sides of -3x+2y=2
-3x+3+2y+3=2+3
closer.... write +3x (not +3) and when we add things to both sides, we do it only once per side (this is different from multiplying or dividing)
+3x-3x+2y=2+3x
yes. now notice on the left side 3x take away 3x is 0x or just 0 you get 2y= 2+3x normally we write the "x term" first.... we are adding and 2+3x is the same as 3x+2 (order can be switched) so 2y = 3x+2 now divide by 2 (when dividing, we have to divide *every* term)
2y/2=3x/2+2/2 1y=1.5x+1
yes. or just y = 1.5x +1 in geometry, we normally keep the slope 1.5 as a fraction. the slope 1.5 is the same as 1.5/1 change in y is 1.5 divided by change in x (1) but we don't want 1.5 because you can't plot decimals. so instead, write 1.5 as 3/2 so change in y (3 ) divided by change in x (2) are nice numbers. we have y = (3/2) x + 1 can you pick an x that gives a nice y ?
1
what is y when x is 1 ?
do i put 1 in the equation
yes...everywhere you see x, erase the x, and put in 1 instead and remember (3/2)x is short for (3/2) times x
i got 2 1/2
yes, so (1, 2 1/2) or (1,2.5) or (1, 5/2) (all are the same thing) but you don't like fractions or decimals. maybe a different x will give a nicer y ?
2
and x=2 means y = ?
4
so (2,4) is nice now use the slope 3/2 = change in y divided by change in x to find another point .
1.5,0.5
how did you get that ?
3/2 and 2/4
change in x means you add that to the x change in y means you add that to the y so if you are at (2,4) and the slope is 3/2 you know the change in x is the bottom number (the 2) and the top number is the change in y (the 3)
so do i add 2+2 and 3+4
yes
4,7
now you need one more point. you can also go backwards from (2,4) if you go -2 in the x direction, you go -3 in the y direction notice that (-3/-2 is the same slope as 3/2)
yeah
can you find a 3rd point ?
wait what two points do i have so far
2,4 and 4,7
2,4 and 3,2
ok
definitely NOT 3,2 (if you put x=3 in the equation you will not get y=2)
ok so to get my 3rd point do i do 2+4 and 3+7
yes, that will work
(2,4) (4,7) (6,10) are my three points?
if you plot them and draw a line through them you should get a nice line
ok thank you can you please help me with one more problem
notice the x values go 2,4,6 up by 2 and the y values go 4,7,10 up by 3 that means the slope is 3/2 (change in y divided by change in x is 3/2 ) notice if you go backwards: x down by 2, y down by 3 you get (0,1)
yeah
post the next one.
Join our real-time social learning platform and learn together with your friends!