\(A=\left(\frac{2.18-1}{18}\right)\left(\frac{2.18-2}{18}\right)\left(\frac{2.18-3}{18}\right)....\left(\frac{2.18-35}{18}\right)\left(\frac{2.18-36}{18}\right)\left(\frac{2.18-37}{18}\right)...\left(\frac{2.18-100}{18}\right)\)

\(=\frac{35}{18}.\frac{34}{18}.\frac{33}{18}...\frac{1}{18}.\frac{0}{18}.\frac{-1}{18}...\frac{-64}{18}=0\)

a) 32 : 4 : 2 = 8 : 2 = 4 

     32 : 4 : 2 = 32 : 2 = 16 

b) 18 : 2 x 3 = 18 : 6 = 3

     18 : 2 x 3 = 9 x 3 = 18

\(18^{18}:18^{17}+2^3.3^2=18^{18-17}+8.9=18+72=90\)

A

A

A

= 19 cách giải thì chờ OLM duyệt 

nhanhnhanh giup mk vs

Đặt A = \(\frac{\frac{1}{18}+\frac{2}{17}+....+\frac{18}{1}+18}{\frac{1}{18}+\frac{1}{17}+....+\frac{1}{1}}\)

Xét TS (tử số) của A ta có:

TS = \(\frac{1}{18}+\frac{2}{17}+...+\frac{18}{1}+18\)

\(TS=\left(\frac{1}{18}+1\right)+\left(\frac{2}{17}+1\right)+...+\left(\frac{18}{1}+1\right)\) (chia 18 ra 18 phần 1 đơn vị cộng lại cho mỗi phân số)

\(TS=\frac{19}{18}+\frac{19}{17}+...+\frac{19}{1}=19.\left(\frac{1}{18}+\frac{1}{17}+...+\frac{1}{1}\right)\)

Thay lại TS vào A ta có:

\(A=\frac{19.\left(\frac{1}{18}+\frac{1}{17}+...+\frac{1}{1}\right)}{\left(\frac{1}{18}+\frac{1}{17}+...+\frac{1}{1}\right)}=19\)

Đáp án :

a) \(135+\left(-2\right).14-135+28\)

\(=135+\left(-28\right)-135+28\)

\(=135-28-135+28\)

\(=135-135+28-28=0\)

b) \(-18.2+18.\left(-6\right)+\left(-18\right).3\)

\(=18.\left(2+6+3\right)=18.11=198\)

a) \(135+\left(-2\right)\cdot14-135+28\)

\(=135+\left(-28\right)-135+28\)

\(=\left(135-135\right)+\left[\left(-28\right)+28\right]\)

\(=0+0\)

\(=0\)

b) \(-18\cdot2+18\cdot\left(-6\right)+\left(-18\right)\cdot3\)

\(=-18\cdot2+\left(-18\right).6+\left(-18\right).3\)

\(=-18\cdot\left(2+6+3\right)\)

\(=-18\cdot11\)

\(=-198\)

\(a)135+\left(-2\right).14-135+28\)

\(=135+\left(-28\right)-135+28\)

\(=135-135+\left(-28\right)+28\)

\(=0+0\)

\(=0\)

\(b)\left(-18\right).2+18.\left(-6\right)+\left(-18\right).3\)

\(=\left(-36\right)+\left(-108\right)+\left(-54\right)\)

\(=\left(-144\right)+\left(-54\right)\)

\(=\left(-198\right)\)

\(-18.2+18.\left(-6\right)+\left(-18\right).3\)

\(=-18.2+\left(-18\right).6+\left(-18\right).3\)

\(=-18.\left(2+6+3\right)\)

\(=-18.11\)

\(=-198\)

-18.2+(-18).6+(-18).3

=-18.(2+6+3)

=-18.12

= ..... ( tự tính nha )

-18×2+18×(-6)+(-18)×3. =18×(-2)+18×(-6)+18×(-3) =18×[-2+(-6)+(-3)]. =18×(-11). =-189

\(x\sqrt{18}-\sqrt{18}=x\sqrt{18}+4\sqrt{2}\\ \Rightarrow-3\sqrt{2}=4\sqrt{2}\left(vô.lí\right)\)

\(x\sqrt{18}-\sqrt{18}=x\sqrt{18}+4\sqrt{2}.\)

\(\Leftrightarrow x\sqrt{18}-\sqrt{18}-x\sqrt{18}=4\sqrt{2}.\)

\(\Leftrightarrow-3\sqrt{2}=4\sqrt{2}\) (vô lý).

<=> x\(\sqrt{18}\) - x\(\sqrt{18}\) = \(4\sqrt{2}\) + \(\sqrt{18}\)

<=> 0x = \(4\sqrt{2}\) + \(3\sqrt{2}\)

<=>0x = \(7\sqrt{2}\)