ashleyb
Solve. x^2 + x = 20
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Izzy25
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okay so first you move 20 over the = sign
UnkleRhaukus
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\[x^2+x=20\]
\[x^2+x-20=0\]
\[x=\frac{-b\pm\sqrt{b^2-4ax}}{2a}\]
Izzy25
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so it becomes this:
|dw:1343183162557:dw|
Izzy25
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and then like the guy did above you use the QUADRATIC FORMULAAA .. it's quite hectic i tell you... do you need help with that... i can walk you through it
ashleyb
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i tried that way already but my hw is asking me to find two x's
Izzy25
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that is it
ashleyb
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oh..then i must of did something wrong
Izzy25
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so you don't know how to do it because the quadratic formula DOES give u 2 answers
UnkleRhaukus
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\[a=1,\qquad b=1,\qquad c=-20\]
Izzy25
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still want me to walk you though it?
Izzy25
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* through
Izzy25
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or unkleR can help u that is...
ashleyb
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|dw:1343183363230:dw|when i did the quadraric formula i got
Izzy25
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GOODDDD
Izzy25
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okay so now just do it one by one... your looking at 2 equations!
Izzy25
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|dw:1343183439776:dw|
Izzy25
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or you could leave it like that... idk what ur teacher likes best
ashleyb
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oh okay. i understand now. thx for ur help
Izzy25
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UR WELCOME
.Sam.
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You can use sum of roots and product of roots,
x^2-(SOR)+(POR)=0
SOR=a+b=-1
POR=ab=-20
Simultaneous equations,
a=-5, b=4
Roots are
x=-5, x=4