8. Bỏ dấu ngoặc rồi tính: a) ( 17 – 229) + ( 17 - 25 + 229) ; b) ( 125 – 679 + 145) – ( 125 – 679 )9. Tìm x biết: a) 15 – ( 4 – x) = 6 ; b) - 30 + ( 25 – x) = - 1 ;c) x – ( 12 – 25) = -8 ; d) ( x – 29 ) – ( 17 – 38 ) = - 910. Tìm số nguyên x biết: a) x – 5 = - 1...
Đọc tiếp
8. Bỏ dấu ngoặc rồi tính:
a) ( 17 – 229) + ( 17 - 25 + 229) ; b) ( 125 – 679 + 145) – ( 125 – 679 )
9. Tìm x biết: a) 15 – ( 4 – x) = 6 ; b) - 30 + ( 25 – x) = - 1 ;
c) x – ( 12 – 25) = -8 ; d) ( x – 29 ) – ( 17 – 38 ) = - 9
10. Tìm số nguyên x biết: a) x – 5 = - 1 ; b) x + 30 = - 4; c) x – ( - 24) = 3 ; d) 22 – ( - x ) = 12; e) ( x + 5 ) + ( x – 9 ) = x + 2 ; f) ( 27 – x ) + ( 15 + x ) = x – 24 .
Bài 10:
a: x-5=-1
=>x=-1+5
=>x=4
b: x+30=-4
=>x=-4-30
=>x=-34
c: x-(-24)=3
=>x+24=3
=>x=3-24
=>x=-21
d: 22-(-x)=12
=>22+x=12
=>x=12-22
=>x=-10
e: (x+5)+(x-9)=x+2
=>x+5+x-9=x+2
=>2x-4=x+2
=>2x-x=4+2
=>x=6
f: (27-x)+(15+x)=x-24
=>x-24=27-x+15+x=42
=>x=42+24
=>x=66
Bài 9:
a: 15-(4-x)=6
=>4-x=15-6=9
=>x=4-9=-5
b: -30+(25-x)=-1
=>-30+25-x=-1
=>-5-x=-1
=>x+5=1
=>x=1-5
=>x=-4
c: x-(12-25)=-8
=>x-(-13)=-8
=>x+13=-8
=>x=-8-13
=>x=-21
d: (x-29)-(17-38)=-9
=>x-29-(-21)=-9
=>x-29+21=-9
=>x-8=-9
=>x=-9+8
=>x=-1
Bài 8:
a: (17-229)+(17-25+229)
=17-229+17-25+229
=34-25
=9
b: (125-679+145)-(125-679)
=125-679+145-125+679
=145