\(311-x+82=46+x-21\)

           \(393-x=x+25\)

                 \(x+x=393-25\)

                       \(2x=368\)

                         \(x=184\)

\(311-x+82=46+x-21\)

           \(393-x=x+25\)

                 \(x+x=393-25\)

                       \(2x=368\)

                          \(x=184\)

\(-\left(x-3+84\right)=-x+70-71-5\)

      \(-x+3-84=-x+70-71-5\)

               \(-x-81=-x-6\)

                  \(-x+x=-6+81\)

                            \(0x=75\)

=> pt vô nghiệm

điên à ko thấy người ta hỏi à muốn hỏi nữa thì cút

- ( x - 3 + 84 ) = ( x + 70 - 71 ) - 5

- x + 3 - 84     = x + 70 - 71 - 5

- x - x             = 70 - 71 - 5 - 3 + 84

- 2x                = 75

    x                = -37,5

\(1.311-x+82=46+\left(x-21\right)\\ 311+82-x=46-21+x\\ 393-x=25+x\\ 393-x-25-x=0\\ 393-25-x-x=0\\ 368-2x=0\\ \Rightarrow-2x=368\\ x=368:\left(-2\right)\\ x=-184\)

\(2.-\left(x-3+85\right)=\left(x+70-71\right)-5\\ -x+3-85=x+70-71-5\\ -x-82=x-6\\ -x-82-x+6=0\\ -2x-76=0\\ -2x=76\\ x=76:\left(-2\right)\\ x=-38\)

\(3.\left(-x+821+534\right)=499+\left(x-84\right)\\ -x+821+534=499+x-84\\ -x+1355=x+415\\ -x+1355-x-415=0\\ -2x+940=0\\ -2x=-940\\ x=-940:\left(-2\right)\\ x=470\)

\(4.x+96=\left(443-x\right)-447\\x+96=443-x-447\\ x+96=-x-4\\ x+96+x+4=0\\ 2x+100=0\\ 2x=-100\\ x=-100:2\\ x=-50 \)

phá ngoặc. chuyển vế đổi dấu là đc

134;135;136 SBT 6 DAY

:-) 

me too

\(311-x+82=46\left(x-21\right)\)

<=> \(311+82-46+21=x+x\)

<=> \(2x=368\)

<=> \(x=184\)

\(-x+821+534=499+x-84\)

<=> \(-x-x=499-84-821-534\)

<=> \(-2x=-940\)

<=> \(x=470\)

\(-\left(x-3+85\right)=x+70-71-5\)

<=> \(-x+3-85=x-6\)

<=> \(-x-x=-6-3+85\)

<=> \(-2x=76\)

<=> \(x=-38\)

$311-x+82=46\left(x-21\right)$

<=> $311+82-46+21=x+x$

<=> $2x=368$

<=> $x=184$

$-x+821+534=499+x-84$

<=> $-x-x=499-84-821-534$

<=> $-2x=-940$

<=> $x=470$

$-\left(x-3+85\right)=x+70-71-5$

<=> $-x+3-85=x-6$

<=> $-x-x=-6-3+85$

<=> $-2x=76$

<=> $x=-38$

\(a)\)

\(x+\left(x+1\right)+\left(x+2\right)+...+70+71=71\)

\(\Rightarrow x+\left(x+1\right)+\left(x+2\right)+...+70=0\)

Gọi số số hạng trong dãy số đó là \(a\)\(\left(a\ne0\right)\)

\(x+\left(x+1\right)+\left(x+2\right)+...+70\)

\(\Rightarrow\frac{\left(x+70\right).a}{2}\)

\(\Rightarrow\frac{\left(x+70\right).a}{2}=0\)

\(\Rightarrow\left(x+70\right).a=0\)

\(\Rightarrow x+70=0\)

\(\Rightarrow x=\left(-70\right)\)

\(b)\)

\(85+84+83+...+\left(x+2\right)+\left(x+1\right)+x=85\)

\(\Rightarrow84+83+...+\left(x+2\right)+\left(x+1\right)+x=0\)

Gọi số số hạng trong dãy tính là \(a\)\(\left(a\ne0\right)\)

\(84+83+...+\left(x+2\right)+\left(x+1\right)+x\)

\(\Rightarrow\frac{\left(x+84\right).a}{2}\)

\(\Rightarrow\frac{\left(x+84\right).a}{2}=0\)

\(\Rightarrow\left(x+84\right).a=0\)

\(\Rightarrow x+84=0\)

\(\Rightarrow x=\left(-84\right)\)

a) 311 - x + 82 = 46 + (x - 21)

311 - x + 82 = 46 + x - 21

-x - x = 46 - 21 - 311 - 82

-2x = -368

x = -368 : (-2)

x = 184

b) -(x - 3 + 85) = (x + 70 - 71) - 5

-x + 3 - 85 = x + 70 - 71 - 5

-x - x = 70 - 71 - 5 - 2 + 85

-2x = 77