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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: giúp mik vs mn ơiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii (x-5) ² +|y ² -4|=0

Toán Lớp 7: giúp mik vs mn ơiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
(x-5) ² +|y ² -4|=0

Comments ( 2 )

  1. (x-5)^2 + |y^2 – 4| = 0
    Vì (x-5)^2 ≥ 0∀x
    |y^2 – 4|≥0∀y
    => $\left \{ {{(x-5)^2=0} \atop {|y^2-4|=0}} \right.$ 
    <=> $\left \{ {{x-5=0} \atop {y^2-4=0}} \right.$ 
    <=> $\left \{ {{x=5} \atop {y^2=4}} \right.$ 
    <=> $\left \{ {{x=5} \atop {y=±2}} \right.$ 
    Vậy (x,y) = {(5;2);(5;-2)}

  2. Ta có : ( x – 5 ) ≥ 0 với mọi x
               | y^2 – 4 | ≥ 0 với mọi x
    => ( x – 5 )^2 + | y^2 – 4 | ≥ 0
    Mà ( x – 5 )^2 + | y^2 – 4 | = 0
    ⇔ ( x – 5 )^2 = 0
    => x – 5         = 0
    => x               = 5
    ⇔ | y^2 – 4 | = 0
    => y^2 – 4 = 0
    => y^2       = 4
    => y^2       = ±2^2
    => y            = ±2
    Vậy x = 5 ; y = ±2
     

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222-9+11+12:2*14+14 = ? ( )

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