I'm doing slopes for my homework and every time I get to graphs it's wrong. For example, questions like y=4/5x-3. I know that b= (0,-3) but I can't plot m.
#I can't make graphs
silent peak
timid mirageBOT
I'm doing slopes for my homework and every time I get to graphs it's wrong. For ...
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polar mantle
The easiest way is to pick two values for x and solve the equation... some values of x are easier to solve than others, depending on the equation
polar mantle
If you pick 0 for your first value of x, then solve, you'll have the matching y coordinate... for that equation, you'll want to multiply 4 against something that will make a product that divides by 5 nicely
Depending on how picky your teacher is, whole numbers are usually easier to graph than fractional coordinates
silent peak
So if m= 4/5 then x=5 (4/5×5=4)?
random crescent
but you also need to consider the b part
so like
you have a point, when x=5, your y is equal to
something specific
polar mantle
Yep... then like random said, complete the rest of the equation, and you're left with y = something
So your second point will be (5, something)
polar mantle
Why do you feel like that?
random crescent
5,2 is a point on the line yea
lapis mural
use desmos
random crescent
you can replace the x and y with the respective
lapis mural
guys what are we talking about
random crescent
$1=\frac45 \times 5 - 3\\1=4-3$
silent peak
use desmos
I used desmos first and every time it said the answers were wrong
full vortexBOT
!𒐪 ɹɐupoɯ⇂ㄥ8𝟝 𒐪!
random crescent
I used desmos first and every time it said the answers were wrong
what is the question lol
lapis mural
meh just rise/run it
silent peak
Why do you feel like that?
Translating the words into math that I can understand isn't going so well
lapis mural
count squares
silent peak
what is the question lol
f(x)=3/5x-7
silent peak
It's wrong
silent peak
Yes
I'm trying to graph it
The blue line is wrong and the answer desmos gave me wasn't an option because the graph doesn't go that far but now the thing just says it's wrong
random crescent
okay you might want to understand how slope works
so the top number is how many tiles the y value changes per the bottom number, how many tiles the x value changes
polar mantle
so the top number is how many tiles the y value changes per the bottom number, h...
I wonder if Reid has heard "rise over run"
random crescent
oh ye
polar mantle
That's another way to get your second point
Looks like we switched equations while I was sketching
silent peak
The one I gave was the original question but it reset to make sure I'm not cheating
polar mantle
Ok
silent peak
So far I can identify the different parts of the equation and make it into different forms it's just understanding how the slope applies to the graph is where I'm stuck
random crescent
rise over run
silent peak
y/x=3/5 so move the second point to (5,3)?
polar mantle
You can either use the simple counting method that random mentioned... your slope is 3/5, so count up 3 (because your slope is positive) and right 5, or pick a new number and repeat the process
silent peak
Okay
polar mantle
It looks like you might be counting them backwards.. look at the change in y value (rise) compared to the change in x value (run) in the correct answer
See how they're backwards from your answer?
silent peak
Yeah I see it
I'm getting closer. Mine went through (3,0) but it should've been (6,0)
silent peak
I finally got one
Mark at the y-intercept
Go across x and up y
Makes sense now but I kept getting confused over the slope
polar mantle
Where are you getting your x and y values to go across and up?
silent peak
The question was y=4/5x-6 so from (0,-6) I went across 5 and up 4 which gave me (-5,-2) I think. It moved to the next question so I can't see for sure
silent peak
5?
polar mantle
Yep... are you sure you got (-5, -2)?
silent peak
Not completely
silent peak
polar mantle
So.. let's try this...
Starting from the origin (0, 0) you've got a line that passes through the point (3, 7)
What's the slope?
silent peak
7/3
polar mantle
Awesome
So let's say your equation is:
y = 7/3x + 4
Where does the line intercept the y-axis?
silent peak
b=4
polar mantle
3 for 3... so I'm honestly confused on how you're not getting the correct answers on your homework!
Seems like you understand it well enough
silent peak
Because I always focused more on the equations and half assed my way through graphs
polar mantle
On your homework, do you have some scratch paper next to you so you can graph the points out, draw the line, and then answer the question?
Or are you trying to just look at the screen and answer it?
silent peak
I'm using my iPad for scratch working it out and answering on my computer
silent peak
It's moved on to undefined graphs
polar mantle
So you're starting to get the correct answers? Or.. you're just moving on?
And who keeps doing that??!
gift heart weirdness
silent peak
You helped with me 6, I knew how to answer 7, and now I'm stuck on 8. I know it's vertical and doesn't have a function but I don't know how to translate that into my computers graph.
polar mantle
Ah, ok... so how would you graph a flat, horizontal line?
Something parallel to the x-axis, where the y value never changes
silent peak
Straight across through y
polar mantle
And what would the formula for that look like?
silent peak
I'm not sure
y=z, No x
polar mantle
Nope
silent peak
Worth a shot
polar mantle
Heh...
It's just y = 3
Or whatever your y-intercept is
y always equals that number, no matter what
even if x changes, y always = 3
So now... if you have a vertical line, x always equals the same value, right?
silent peak
In this case x=8
silent peak
It requires me to make a line
I think the last walk through used (x,0) and (x,1) so ig it'll be (8,0), (8,1)
silent peak
Got it
No desmos kept giving me the wrong answer
I used to wish for homework but now I never want to see it again
polar mantle
OHHHH....
That might be your problem, yep
In fact, that is exactly your problem... you've been giving it the inverse function
Which is why your slope was backwards
silent peak
Of course 😑
polar mantle
Hey, at least it's an easy fix!
silent peak
Yup
I just put in my notes that the slope is relative to b which makes sense since b is a constant and the slope uses a variable
polar mantle
Slope doesn't use a variable
silent peak
y=mx+b?
polar mantle
No... y is also affected
silent peak
Ughhhh
polar mantle
That's why you get a new y value for every x value you plug in
silent peak
Okay
So b is constant, everything is touched by x, m is slope, don't do it backwards.
Because functions?
polar mantle
b is constant, and for your purpose right now, m is constant
The slope of a straight line never changes, right?
it's always 3/5 or whatever
We're just multiplying the slope m by the x coordinate we want more information about in order to obtain the corresponding y value
polar mantle
Because functions?
Because functions 😉
silent peak
I can't wait to get back to pre-calc I'm already tired of graphs
It's moved on to making a graph after switching around the numbers to slope intercept form
Feels like I'm close tho
polar mantle
heads up... in pre-calc, your slopes are going to start changing based on the value of x
silent peak
So what I'm doing now will be considered backwards for pre-calc?
silent peak
I wonder if it's too late to drop out /j
polar mantle
This is a simple graph of the sin function... as you move along the x axis, the slope changes.. sometimes positive, sometimes negative, etc.
Heh... yeah, it can get rough
But for your straight lines, for now, consider slope (m) to be constant
silent peak
At least it's thorough ig
