`\color{blue}\text {#DuyNam}`
`1,`
`a, = 2354 - 45 - 2354`
`= (2354-2354)-45`
`=0-45=45`
`b,`
`=-2009 - 234+2009`
`= (-2009+2009)-234`
`=0-234=-234`
`c,`
`= 16+23+153-16-23`
`= (16-16)+(23-23)+153`
`= 0+0+153=153`
`d,`
`= 134-167+45-134-45`
`= (134-134)+(45-45)-167`
`= 0+0-167=-167`
`2,`
`a,`
`= 1267-196-267-304`
`= (1267-267) -(196+304)`
`= 1000-500=500`
`b,`
`= 2002-79+15+79-15`
`= 2002-(79-79)+(15-15)`
`= 2002-0+0=2002`
`c,`
`= 3965-2378-437+1378-528`
`= 3965- (2378-1378)-(437+528)`
`= 3965- 1000 - 965`
`= (3965-965)-1000`
`= 3000-1000=2000`
`d,`
`= 435-167-89-435+89`
`= (435-435)+(89-89)-167`
`= 0+0-167=-167`
`3,`
`a,`
`=279-1987+ -18+1987-279`
`= (279-279)+(1987-1987) + (-18)`
`= 0+0+-18=-18`
`b,`
`= -3251-415+2000+585-251`
`= -3666+2000+585-251`
`= -1666+585-251`
`= -1332`
`c,`
`= 71+30-18+ -30+118`
`= (30+ -30)+(118-18)+71`
`= 0+100+71=171`
`d,`
`= -(25-15)+ -(26-16)+ -(27-17)+ -(28-18)+ -(29-19)`
`= -10+ -10+ -10+ -10+ -10=-50`
`4,`
`a,`
`x+7=0`
`x=0-7`
`x=-7`
`b,18-x=-8-(-13)`
`18-x=5`
`x=18-5`
`x=13`
`c, (-12)-x-(-19)=0`
`(-12)-x+19=0`
`(-12)-x=0-19`
`(-12)-x=-19`
`x=(-12)-(-19)`
`x=(-12)+19`
`x=7`
`d, (-14)+x-7=-10`
`(-14)+x=-10+7`
`(-14)+x=-3`
`x=(-3)-(-14)`
`x=(-3)+14`
`x=11`
`5,`
`a, (-5)+x=7`
`x=7- (-5)`
`x=7+5`
`x=12`
`b, (-14)-x+(-15)=-10`
`(-14)-x=(-10)-(-15)`
`(-14)-x=(-10)+15`
`(-14)-x=5`
`x=(-14)-5`
`x=-19`
`c, 12+x+(-5)=-18`
`12+x=(-18)-(-5)`
`12+x=(-18)+5`
`12+x=(-13)`
`x=(-13)-12`
`x=-25`
`d, x-(-19)-(-11)=0`
`x+19+11=0`
`x+19=0-11`
`x+19=-11`
`x=(-11)-19`
`x=-30`
`6,`
`a,` Thay `a=-47`
`-> (-47)+11- (-47)-29 = (-47)+11+47-29`
`= (-47+47)+11-29=0+11-29=-18`
`b,` Thay `a=-25, b=23`
`-> (-25)-23-22+25+23 =(-25+25)+(23-23)-22 =0+0-22=-22`
`c,` Thay `a=-20, b=14, c=-15`
`-> 14-5+(-20)-6-(-15)+7-(-20)+9=14-5+(-20)-6+15+7+20+9=34`
`d,` Thay `a=-153, b=-291`
`-> -153+21-(-153+21- -291)=-153+21+153-21+ -291 =(-153+153)+(21+ -21)+ -291=0+0+ -291=-291`
*câu b bài 3 hơi rối ._.
Bạn tách bài ra để hỏi được không bạn nhỉ? Vậy sẽ giải được nhanh hơn á!
Mình chỉnh lại câu `1, a,` ;-;
`a, = 2354-45-2354 = (2354-2354)-45 = 0-45 = -45`
