Tìm x ∈ Z biết a)-x+8=-7 b)-148-2x=-260 c)12x+450=15x-162 d)-/x-5/=-7 e)(x-2).(5-x)=0 g)x^3=-64 h)(x-1)^5=-32 i)-(x+1)^2+81=0

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1. $a, -x+8=-7$
   $⇔-x=-7-8$
   $⇔-x=-15$
   $⇔x=15$

   $b, -148-2x=-260$
   $⇔-2x=-260+148$

   $⇔-2x=-112$
   $⇔x=56$

   $c, 12x+450=15x-162$

   $⇔12x-15x=-162-450$
   $⇔-3x=-612$
   $⇔x=204$
   $d, \left \{ {{-(x-5)=-7} \atop {-(5-x)=-7}} \right.$

   $⇔\left \{ {{-x+5=-7} \atop {-5+x=-7}} \right.$

   $⇔\left \{ {{-x=-12} \atop {x=-7+5}} \right.$

   $⇔\left \{ {{x=12} \atop {x=-2}} \right.$
   $e, (x-2)(5-x)=0$

   $⇔\left \{ {{x-2=0} \atop {5-x=0}} \right.$

   $⇔\left \{ {{x=2} \atop {x=5}} \right.$

   $g, x³=-64$

   $⇔x³=-4³$
   $⇔x=-4$

   $h, (x-1)^5=-32$
   $⇔(x-1)^5=-2^5$

   $⇔x-1=-2$
   $⇔x=-2+1$
   $⇔x=-1$

   $i, -(x+1)²+81=0$
   $⇔-(x+1)²=-81$
   $⇔\left \{ {{x+1=9} \atop {x+1=-9}} \right.$

   $⇔\left \{ {{x=8} \atop {x=-10}} \right.$ 

    

   Trả lời

2. a) -x+8=-7

   -x=-7-8

   -x=-15

   x=15

   Vậy x=15

   b)-148-2x=-260

   -2x=-260+148

   -2x=-112

   x=-112/(-2)

   x=56

   Vậy….

   c)12x+450=15x-16

   12x-15x=-16-450

   -3x=-466

   x=-466/(-3)

   x=466/3

   Vậy…

   d) -/x-5/=-7

   =>x-5=7

   =>x=7+5

   =>x=12

   Vậy…

   e)(x-2).(5-x)=0

   =>x-2=0 hoặc 5-x=0

   x=0+2                x=5-0

   x=2                     x=5

   Vậy….

   g) x³=-64

   =>x=-4

   Vậy….

   h)(x-1)^5=-32

   =>x-1=2

   =>x=3

   Vậy….

   i)-(x+1)^2+81=0

   -(x+1)^2=-81

   =>x+1=9 hoặc x+1=-9

   x=8                     x=-10

   Vậy…

   Chúc bn hc tốt, cho mk 5 sao và ctlhn nha^^

    

   Trả lời