Bài 2 :
a , 900 + ( 120 :1 + 0 : 250 )
= 900 + ( 120 + 0 )
= 900 + 120
= 1020
b, 17119: ( 119 -714 : 7 ) + 3302 : 13 - 567
= 17119 : ( 119 - 102 ) + 254 - 567
= 17119 : 17 + 254 - 567
= 1007 + 254 - 567
= 1261 - 567 = 694
c , $9^{4}$ - 8 . $9^{3}$
= $9^{4}$ - 5832
= 729
d , $2^{6}$ : $2^{4}$ + $3^{2}$ - $2^{3}$
= $2^{2}$ + 1
= 5
Bài 3 :
a, 12x + 3x - 5x =250
=> 15x - 5x = 250
=> 10x = 250
=> x = 25
b, ( 2x +8 ) : 4 = ( x+1 )
=>2x + 8 = 4.(x + 1)
=>2x+8 = 4x+4
=>2x - 4x = 4 - 8
=>-2x = -2
=>x = 1