Tìm số nguyên x, biết rằng :
a ) ( 3 + x ) . 5 – 14 = – 49
b ) – 72 : ( x – 2 )^3 = 9
c ) x + ( – 12 ) = 16 – x
d ) 2| x | + | – x | = 9
Tìm số nguyên x, biết rằng :
a ) ( 3 + x ) . 5 – 14 = – 49
b ) – 72 : ( x – 2 )^3 = 9
c ) x + ( – 12 ) = 16 – x
d ) 2| x | + | – x | = 9
a,(3+x)×5-14=-49
⇒15+5x-14=-49
⇔5x+1=-49
⇔ 5x=-50
x=-10
b,-72:(x-2)³=9
⇔(x-2)³=-8
⇒x-2=-2
⇔x=0
c,x+(-12)=16-x
⇔x-12=16-x
⇔2x=4
⇔x=2
d,2|x|+|-x|=9
Nếu x≥0
⇒2|x|+|-x|=9
⇒2x+x=9
⇒3x=9
⇒x=1(t/m)