Toán Lớp 7: ai làm đc mình vote 5 sao
tim x
a)(x-4) mũ 2=25
b)(x+9) mũ2 +7=43
c)(x-6)mũ2 < hoặc bằng 0
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Toán Lớp 7: ai làm đc mình vote 5 sao
tim x
a)(x-4) mũ 2=25
b)(x+9) mũ2 +7=43
c)(x-6)mũ2 < hoặc bằng 0
Comments ( 2 )
(x-4)^2=25
=>(x-4)^2=(+-5)^2
=>[(x-4=5),(x-4=-5):}
=>[(x=5+4),(x=-5+4):}
=>[(x=9),(x=-1):}
Vậy x\in{9;-1}
b)
(x+9)^2+7=43
=>(x+9)^2=43-7
=>(x+9)^2=36
=>(x+9)^2=(+-6)^2
=>[(x+9=6),(x+9=-6):}
=>[(x=6-9),(x=-6-9):}
=>[(x=-3),(x=-15):}
Vậy x\in{-3;-15}
c)
(x-6)^2le0
Ta có:
(x-6)^2ge0forallx
Mà (x-6)^2le0
=>(x-6)^2=0
=>x-6=0
=>x=0+6
=>x=6
Vậy x=6