Question

resolva x+y=7 x.y=10

Answer 1

x + y = 7
x.y = 10

x = 7 - y

(7 - y)y = 10
7y - y² = 10
- y² + 7y - 10 = 0 ( - 1)
y² - 7y + 10 = 0
a = 1; b = - 7; c = 10

Δ = b² - 4ac
Δ = (-7)² - 4.1.10
Δ = 49 - 40
Δ = 9

y = - b +/- √Δ  = - ( -7) +/- √9
           2a                2.1

y = 7 + 3 = 10/2 = 5
         2

y = 7 - 3 = 4/2 = 2
        2

y = 5
x = 7 - y
x = 7 - 5
x = 2

y = 2
x = 7 - y
x = 7 - 2
x = 5

Resp.: x = 5 e y = 2 ou x = 2 e y = 5
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