Solve the system y = -x + 7 and y = 0.5(x - 3)2
@Flamo multiply both sides of y = -x + 7 by 2.
2y = -2x + 14
Next, multiply both sides of \(y = 0.5(x - 3)^2\) by 2.
2y = 1(2x - 6)^2?
More like \(2y = 1(x - 3)^2\)
Oh.
Next you set both expressions for 2y equal to each other.
Hmm..
I have this written down. y = -x + 7 and y = 0.5(x - 3)^2 0.5(x - 3)^2 = -x + 7 Multiply Both sides by 2 -2x + 14 = x^2 - 6x + 9
So that's incorrect?
It's the exact same thing actually.
Oh, So what do you need to do *from there*?
Solve for x, which is what we were doing previously.
Oh
I was trying to show you how to do it but once again, you have introduced something else which is adding to your confusion.
I did? Oh...
The Teacher says, After -2x + 14 = x^2 - 6x + 9 <---- You need to Simplify: x^2 - 4x - 5 = 0 then factor to figure out the x's, then sub it x's to get y
Yeah, see you did it again. I was showing you how to do it, then you interrupt by introducing "what the teacher said". I don't care what the teacher said.
Oh, You said Solve for x. Right?
No no no no, You said: Next you set both expressions for 2y equal to each other.
Right?
Yes, I did and then you proceeded to post what your teacher said.
Oh, Sorry. I was Confused. Let's Continue from there then.
Okay, still waiting for you to set the expressions for 2y equal to each other.
Yeah, i'm doing that right now.
2y = -2x + 14 and 2y = 1(x - 3)^2
Right?
Yes, and so since we know 2y = 2y, then what expressions are equal to each other?
Uhh, I don't know.. ;-;
\(2y = 2y\) means that \(-2x + 14 = (x - 3)^2\)
OH
2y = -2x + 14 || || 2y = 1(x - 3)^2
So You Subtract?
"Wondering how @flamo concluded that equal signs mean subtract".
Oh... They were Sideways, Didn't realize that they were equal Signs...
My bad... ;-;
Okay, the equations are equal, now what? ;-;
You have to post your steps here.
y = -x + 7 and y = 0.5(x - 3)^2 0.5(x - 3)^2 = -x + 7 Multiply Both sides by 2 2y = -2x + 14 and 2y = 1(x - 3)^2 2y = -2x + 14 = 2y = 1(x - 3)^2
That's the steps I've written when we were solving the problem
It's true what you've written except since we need to solve for \(x\) you only include the expressions with \(x\)
Oh? So You take the 2y out on Both equations?
Yes
-2x + 14 = 1(x - 3)^2? Sorry I had to do something, ;-;
@Hero
Finally.... Now question. what is \(1 \times 7 = \)
7
Good so \(1 \times (x - 3)^2\) =
...
Oh.
Uhh (x - 3)^2
Correct. So basically what we have is \(-2x + 14 = (x - 3)^2\)
And we can expand \((x - 3)^2\) using (not FOIL) but distributive property
Oh
So (x - 3) - (3 - x)?
No \((x - 3)^2\) means multiply \((x - 3)\) by itself twice.
Oh... I feel Dumb. ;-; \[(x - 3) \times (x - 3)\]
Which is \[x^2 - 6x +9 \] Right @Hero?
Correct
y = -x + 7 and y = 0.5(x - 3)^2 0.5(x - 3)^2 = -x + 7 Multiply Both sides by 2 2y = -2x + 14 and 2y = 1(x - 3)^2 -2x + 14 = 1(x - 3)^2 -2x + 14 = (x - 3)^2 -2x + 14 = (x - 3) * (x - 3) -2 + 14 = x^2 - 6x + 9
This is what I have so Far. Correct?
@Hero
Looks good
Okay, So now what?
From this: -2 + 14 = x^2 - 6x + 9
Actually the x is missing from 2.
Oops
From this: -2x + 14 = x^2 - 6x + 9
Next subtract 14 from both sides. Then add 2x to both sides.
\[-2x = x^2 - 6x + (-5)\]
Okay, I subtracted 14 from both Sides, now add 2x?
Or Subtract *-2x*?
From Both sides.
It's exactly like I suggested above.
Oh, So \[x^2 - 4x + (-5)\]
Okay, So I added 2x to both sides.
Yeah but you still need to put something on the other side of the equal sign.
0?
0 = x^2 - 4x + (-5)?
Yes correct
Oh, Okay. Now what?
You can re-write the expression above as \(0 = x^2 - 4x - 5\) since \(a + (-b) = a - b\)
Oh, Okay
Okay, I did that, Now what?
\[0 = x^2 - 4x + 5\]
You wrote the equation I wrote above incorrectly.
Oh.. ;-;
\[0 = x^2 - 4x - 5\]
Okay, now what?
Now you factor \(x^2 - 4x - 5\)
(x - 5) (x + 1)
Yeah, but what are your steps to get that?
AC Method?
When I ask "What are your steps?", that implies for you to actually post those steps.
Oh, I used a Calculator, ;-;
Oh, I used a Calculator. ;-;
Okay, I'm about to go take a nap.
...
;-;
I can't stop you... ;/
You have to learn how to factor quadratic expressions. It takes too much time to teach. Review some of the other threads where I've shown other users how. I know you've been watching. Don't pretend you haven't.
Yes, I have been watching.
We have to find two numbers \(m\) and \(n\) such that \(m + n = |b|\) \(m \times n = ac\) We need to find that so that we can input \(m + n\) here in place of \(b\) \(x^2 -(m + n)x - 5\) Obviously \(m + n = 4\) in this case.
\[x^2 - (4)x - 5\]
Or Just 4x
Yes we know that already, but it doesn't get us any closer in terms of factoring. We have to "split the middle term"
2 + 2?
= 4?
2 + 2 are the middle Terms for M and n
No, \(m \times n\) has to equal -5
\(m + n\) has to equal \(4\)
Oh
(m + n) = 4 So m = 2 as well as n. So (2+2) = 4.
\(m\) and \(n\) has to satisfy both requirements. How about \(5 - 1 = 4\) \((5)(-1) =-5\)
So looks like it's going to be \(m = 5\) and \(n = -1\)
Oh.
\[x^2 - 5 + (-1) - 5\]?
Or do You not put it in the equation?
You forgot the x. It's \(x^2 -(5 - 1)x - 5\)
Oh..
And the whole time, the expression should be set equal to zero.
Oh
\[0 = x^2 - (5 - 1)x - 5\]?
Yes, now you have to distribute the negative and the x within the parentheses.
Oh.. Hm..
I don't get it.. Sorry ;-;
Well, I'm going to take a nap. Review the tutorials.
Okay. Have fun... ;-;
I suck.. ;/
...
x^2 - 4x - 5
x^2 = x * x
(x )(x )
-5 = - 5
(x - 5)(x - 1)
):
(x - 5)(x + 1)*
;-;
@Hero you still here?
Never Mind, I took enough of your time anyway
(x - 5)(x + 1)
Check
Hm..
x(x - 1) + 5(x - 1)
x^2 - x + 5x - 5
-x subtract on 5x
x^2 -4x - 5
Oh.
@Shadow
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