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what multiplies to be 30 and adds to be -13

 Mar 25, 2020
 #1
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+1

xy  =  30

x + y = -13   ⇒    y =  -13  - x     sub this into  the first equation

 

x ( -13 - x)  = 30    simplify

 

-13x -x^2 =   30     rearrange   as

 

x^2  + 13x  +  30  =   0     factor  as

 

(x  + 3) ( x + 10 )  =  0

 

Set  each factor to 0  and solve for x  and we get that    x =   -3  or x =  -10

 

We only need to consider either one of these

 

And when x  = -3    then

 

y = -13 - (-3)  =   -10

 

So....the  two   integers are

 

-3  and   -10

 

cool cool cool

 Mar 25, 2020

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