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Mathematics 8 Online
Adovbush:

help ill post attachments

Adovbush:

that first one is uh.. an accident lol

xXGoldenMinaceXx:

@AZ

AZ:

One question at a time, my dude. If you post them all at once, no one's going to bite since that's too daunting. 1) We want to solve it algebraically. We have two equations that both start with y = something we can use the substitution method basically if a = b and a = c then that means b = c So we have y = 3x + 8 y = 3x^2 + 14x - 12 can you set them equal to each other and solve the quadratic function?

Adovbush:

no i can't i'm dumb

AZ:

3x + 8 = 3x^2 + 14x - 12 can you bring 3x to the other side by subtracting it on both sides? and do the same thing to the 8? Subtract 8 on both sides so that way we can get one side to be equal to 0

Adovbush:

no i literally can't i'm pretty dumb

Adovbush:

lol

AZ:

if all you can do is make excuses, you won't get very far 3x + 8 = 3x^2 + 14x - 12 let's subtract 8 on both sides first 3x + 8 - 8 = 3x^2 + 14x - 12 - 8 on the left side of the = sign, +8 - 8 = 0 we're left with 3x = 3x^2 + 14x - 12 - 8 can you simplify it? what is -12 - 8 = ?

Adovbush:

-4

Tonycoolkid21:

wow az the math man :)

AZ:

no -12 MINUS 8 -12 + 8 would have been -4 -12 - 8 is going to be what?

Adovbush:

oh lmao told you i'm dumb haha wow

AZ:

if you take out the negative sign for a minute, it's the same thing as -(12 + 8)

Adovbush:

-20

AZ:

Exactly, so now we have 3x = 3x^2 + 14x - 20 now let's subtract 3x on both sides we're left with 0 = 3x^2 + 14x - 3x - 20 what is 14x - 3x = ?

Adovbush:

11x

AZ:

Good! So now we have 3x^2 + 11x - 20 = 0 To find out the solutions, we need to use the quadratic formula \( x = \dfrac{ -b \pm \sqrt{b^2 - 4ac}}{2a} \) when the equation is \( ax^2 + bx + c = 0\) so for your question a = 3 b = 11 c = -20 can you plug it in to the formula?

Adovbush:

x = -11± pi -11^2 -43-20


23

AZ:

hmm some formatting errors, and no idea where that 'pi' came from \( \dfrac{-11\pm \sqrt{11^2 - 4(3)(-20)}}{2(3)}\) can you simplify it? what is 11^2 what is 4 * 3 * -20 what is 2 * 3

Adovbush:

121 -240 6

AZ:

So now we have \(\dfrac{-11 \pm \sqrt{121 - (240)}}{6}\) what is 121 - (-240) =

Adovbush:

361

Adovbush:

chris hemsworth is kinda hot

AZ:

Now take the square root of 361

Adovbush:

how u do that

Adovbush:

19

Adovbush:

google is my best friend

AZ:

yes so we have \(\dfrac{-11 \pm 19}{6}\) so the two x-values are (-11+19)/6 ?? and (-11-19)/6 = ??

Adovbush:

1.33

Adovbush:

or should i round it to 1.34

AZ:

you can round to 1.34 so that's for (-11+19)/6 what about when it's (-11-19)/6 because remember we had a \(\pm\) so we have two answers, one where we add the two numbers and another where we're doing subtraction

Adovbush:

-5

AZ:

yes so the two x-values are 4/3 (or 1.34) and -5 now we need to find the y-value for those x-values just choose any equation, y = 3x + 8 is the easier one and plug in x = 4/3 and x = -5 what are the y-values?

Adovbush:

idk.

Adovbush:

i don't know how to plug in in math but i know how to plug in in bed

AZ:

y = 3x + 8 plug in x = 4/3 y = (3*4/3) + 8 y = ??

Adovbush:

12

AZ:

so for x = 4/3 then y = 12 so one solution is (4/3 , 12) now what about when x = -5 y = (3*-5) + 8 y = ??

Adovbush:

-7

AZ:

So your two solutions for the first question are (4/3, 12) and (-5, 7)

Adovbush:

thanks a lot

AZ:

You're welcome! Either my computer is lagging or it's QC so just tag me on your next post

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