Question

Determine o ponto de intersecção das retas r e s nos seguintes casos:

{(2x+y+3=0 5x-y-10=0) b) {(2x-3y+7=0  4x+5y-19=0)

Answer 1

a) 2x+y+3=0 ==> 2x + y = - 3
    5x-y-10=0 ==> 5x - y = 10
                                  7y = 7  ==> y = 1
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 2x = - 3 - y ==> 2x = - 3 - 1 ==> 2x = - 4 ==> x = - 2
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P( - 2 , - 1 )

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b) 2x - 3y = - 7(5) 
    4x + 5y = 19(3)

10x - 15y = - 35 
12x + 15y = 57
         22x = 22  ==> x = 1

4x + 5y = = 19 ==> 5y = 19 - 4x

5y = 19 - 4(1) ==> 5y = 19 - 4  ==> 5y = 15 ==> y = 3
                   
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P(1,3)