Bang 1 do

bang 1 nha ban!

bang 1 do.

b: =124-312+76-112+21

=200-424+21

=221-424

=-203

a: =735+23-135+177=600+200=800

b: =124-312+76-112+21=200-424+21=-203

c: =183+21+65-183-21=65

d: \(=-271+37-160+31-137=-500\)

e: =-3a+b-3c+b+3c+2a-2b

=-a

Giải;

1) \(347.222-222.\left(216+184\right):8\) 

\(=347.222-222.400:8\) 

\(=347.222-222.50\) 

\(=222.\left(347-50\right)\) 

\(=222.297\)

\(=65934\) 

2) \(132-\left[116-\left(132-128\right).22\right]\) 

\(=132-\left[116-4.22\right]\) 

\(=132-\left[116-88\right]\) 

\(=132-28\) 

\(=104\) 

3) \(16:\left\{400:\left[200-\left(37+46.3\right)\right]\right\}\) 

\(=16:\left\{400:\left[200-\left(37+138\right)\right]\right\}\) 

\(=16:\left\{400:\left[200-175\right]\right\}\) 

\(=16:\left\{400:25\right\}\) 

\(=16:16\) 

\(=1\) 

4) \(\left\{184:\left[96-124:31\right]-2\right\}.3651\) 

\(=\left\{184:\left[96-4\right]-2\right\}.3651\) 

\(=\left\{184:92-2\right\}.3651\) 

\(=\left\{2-2\right\}.3651\) 

\(=0.3651\) 

\(=0\) 

5) \(46-\left[\left(16+71.4\right):15\right]-2\) 

\(=46-\left[\left(16+284\right):15\right]-2\) 

\(=46-\left[300:15\right]-2\)

 \(=46-20-2\) 

\(=24\)

6) \(3^3.18+72.4^2-41.18\) 

\(=18.\left(27-41\right)+72.16\) 

\(=18.-14+1152\) 

\(=-252+1152\) 

\(=900\)

Giải: (tiếp)

7) \(\left(56.46-25.23\right):23\) 

\(=\left(2576-575\right):23\) 

\(=2001:23\) 

\(=87\) 

8) \(\left(28.54+56.36\right):21:2\) 

\(=\left(1512+2016\right):21:2\) 

\(=3528:21:2\) 

\(=84\) 

9) \(\left(76.34-19.64\right):\left(38.9\right)\) 

\(=\left(2584-1216\right):342\) 

\(=1368:342\) 

\(=4\) 

10) \(\left(2+4+6+...+100\right).\left(36.333-108.111\right)\) 

\(=\left(2+4+6+...+100\right).\left(11988-11988\right)\) 

\(=\left(2+4+6+...+100\right).0\) 

\(=0\) 

11) \(\left(5.4^{11}-3.16^5\right):4^{10}\) 

\(=5.4^{11}:4^{10}-3.16^5:4^{10}\) 

\(=5.4-3.1\) 

\(=20-3\) 

\(=17\) 

12) \(7256.4375-725:3650+4375.7255\) 

\(=4375.\left(7256+7255\right)-\dfrac{29}{146}\) 

\(=4375.14511-\dfrac{29}{146}\) 

\(=63485624,8\) 

Câu 12 ko chắc!

\(=\left(152-148\right)+\left(144-140\right)+\left(136-132\right)+\left(128-124\right)+\left(120-116\right)+\left(112-108\right)+\left(104-100\right)\\ =4+4+4+4+4+4+4=28\)

=(152−148)+(144−140)+(136−132)+(128−124)+(120−116)+(112−108)+(104−100)=4+4+4+4+4+4+4=28

Bài 4:

a: xy=-2

=>\(x\cdot y=1\cdot\left(-2\right)=\left(-2\right)\cdot1=\left(-1\right)\cdot2=2\cdot\left(-1\right)\)

=>\(\left(x,y\right)\in\left\{\left(1;-2\right);\left(-2;1\right);\left(-1;2\right);\left(2;-1\right)\right\}\)

b: \(\left(x-1\right)\left(y+2\right)=-3\)

=>\(\left(x-1\right)\cdot\left(y+2\right)=1\cdot\left(-3\right)=\left(-3\right)\cdot1=-1\cdot3=3\cdot\left(-1\right)\)

=>\(\left(x-1;y+2\right)\in\left\{\left(1;-3\right);\left(-3;1\right);\left(-1;3\right);\left(3;-1\right)\right\}\)

=>\(\left(x,y\right)\in\left\{\left(2;-5\right);\left(-2;-1\right);\left(0;1\right);\left(4;-3\right)\right\}\)

Bài 3:

a: \(x\left(x+9\right)=0\)

=>\(\left[{}\begin{matrix}x=0\\x+9=0\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=0\\x=-9\end{matrix}\right.\)

b: \(\left(x-5\right)^2=9\)

=>\(\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=3+5=8\\x=-3+5=2\end{matrix}\right.\)

c: \(\left(7-x\right)^2=-64\)

mà \(\left(7-x\right)^2>=0\forall x\)

nên \(x\in\varnothing\)

Bài 2:

a: \(\left(-31\right)\cdot x=-93\)

=>\(31\cdot x=93\)

=>\(x=\dfrac{93}{31}=3\)

b: \(\left(-4\right)\cdot x=-20\)

=>\(4\cdot x=20\)

=>\(x=\dfrac{20}{4}=5\)

c: \(5x+1=-4\)

=>\(5x=-4-1=-5\)

=>\(x=-\dfrac{5}{5}=-1\)

d: \(-12x+1=-4\)

=>\(-12x=-4-1=-5\)

=>\(12x=5\)

=>\(x=\dfrac{5}{12}\)