Algebra

Bluelightning

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Hey I need help with algebra 2 homework anyone know the answer I would appreciate it

What two numbers multiplied equal -160 but added equal 12?
 

Kαmi

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Tennis Robot

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So you have to set up a system of equations where x = first number and y = second number.

x + y = 12
xy = -160

From there you isolate a variable of your choice in either of the equations (I will do x in the second one):

x = -160/y

Since x is the same in both equations, you can substitute this solution into the first equation:

(-160/y) + y = 12

-160 + y^2 = 12y

y^2 - 12y - 160 = 0

From there, you use the quadratic formula (x = -b +- sqrt[{b^2 - 4ac}/2a]) and try both solutions in both equations.

Hope this helped :)
 

Bluelightning

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So you have to set up a system of equations where x = first number and y = second number.

x + y = 12
xy = -160

From there you isolate a variable of your choice in either of the equations (I will do x in the second one):

x = -160/y

Since x is the same in both equations, you can substitute this solution into the first equation:

(-160/y) + y = 12

-160 + y^2 = 12y

y^2 - 12y - 160 = 0

From there, you use the quadratic formula (x = -b +- sqrt[{b^2 - 4ac}/2a]) and try both solutions in both equations.

Hope this helped :)


Thanks it did I'll use the equation with the rest of the problems
 

Tennis Robot

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Thanks it did I'll use the equation with the rest of the problems

Oh you don't need to use the quadratic formula for everything :p Even in this example, you could easily just factor the polynomial by finding multiples of the third term that add up to the second one.
 
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