Shido88
Find the Vertex:
f(x)= -3x^2-7x+6
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Shido88
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@saifoo.khan helpppp lol
saifoo.khan
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Hey.
To find vertex there's a shortcut.
Shido88
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uh huh
saifoo.khan
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to find the x-cordinate, use this formula:
-b/2a
saifoo.khan
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-(-7)/2(-3)
Shido88
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that will give me the vertex ?
saifoo.khan
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Yes. "x-cordinate" of vertex.
saifoo.khan
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Solve it first..
Shido88
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kk hold on :)
saifoo.khan
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Holding.. :)
Shido88
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got 7/6
Shido88
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vertex is (h,k) right? so i believe that is the "h" ?
saifoo.khan
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Perfect. ^
saifoo.khan
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Find k now.
Shido88
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how to find k lol ?
saifoo.khan
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Lol. Use GOogle. Jk.
Shido88
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i got it lmao :))
Shido88
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hold on
saifoo.khan
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Okay. so now use 7/6 to find it.
y = -3x^2-7x+6
y = -3(7/6)^2 -7(7/6) + 6
solve.
Shido88
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got decimal :( hate decimal
Shido88
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so the vertex would be : (7/6, -6.24) ?
saifoo.khan
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Should be 121/12
Shido88
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wtf ?
Shido88
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how? :O
Shido88
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-156/25
Shido88
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hey come back here >:o
saifoo.khan
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VERTEX SHOULD BE -7/6. -_-
saifoo.khan
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THE X-CORDINATE.
Shido88
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CALM DOWN !! CAPS WAR XD
saifoo.khan
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ONE NEGATIVE SIGN RUINS EVERYTHING. >_<
Shido88
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so -7/6 because its opposite of 7/6 ?
Shido88
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you suppose to change it everytime ?
Shido88
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how come my teacher didn't change it -_____-
saifoo.khan
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No. we calculated the x-cordinate wrong in the first place.
Shido88
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oh....XD
saifoo.khan
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\[-\frac{b}{2a} \to -\frac{(-7)}{2(-3)}\to \frac{7}{-6} \to -\frac 76\]
Shido88
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ohhhhhhhhh i see now lmao hhahaha :D
Shido88
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omfg...my whole problem is wrong, thanks saif ! lol : XD
Shido88
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+99 medals
saifoo.khan
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;D
Thanks.
Shido88
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hmm instead of 121/10 should i just leave it as 10.08 cuz i have to graph this afterward ?
Shido88
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great now i gotta calculate x-int and y-int :|
let see......
saifoo.khan
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Sure.
Same thing. Depends on in what format your teacher wants
Shido88
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stay there.. lol
saifoo.khan
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Lol. okays.
Shido88
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stuck lol....find x-intercept?
Shido88
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i know let y=0
Shido88
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0=-3x^2-7x+6
Shido88
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-6=-3x^2-7x <-----stuck here..
saifoo.khan
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Use quadratic formula
Shido88
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oh yee
Shido88
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but the way my teacher did it was to set y=0 and just add and divide stuff on left and right side...which is confusing but i suppose we can use quadratic aswell :)
saifoo.khan
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Your teacher must have used the "completing the square" method. It's hella confusing. It confuses me too. :/
Shido88
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yeah thats what that was, completing the square lol....
ok i got y= 7+- sqrt(-23)/-6
and what's next ?
Shido88
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i dont think u can reduce it down or anything right? and u can't even square root a negative
saifoo.khan
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No. We can't reduce.
saifoo.khan
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u can't even square root a negative
Yes you're very right.
Shido88
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ohh i get it, it's 7+- 23i/-6
saifoo.khan
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Roots are: -14 and 0.
saifoo.khan
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Roots are: -3 and 2/3
Shido88
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what? @_@
saifoo.khan
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Haha. Ofcourse not.