Đáp án là 7430 .

=7430

a) -(-1998)-(-271+2998)

=1998+271-2998

=(1998-2998)+271

=-1000+271

=-729

b) -31.25+31.119-31.(-6)

=31.(-25+119+6)

=31.100

=3100

c)-79.(73-27)-73.(-79+27)

=-79.73+79.27+79.73-27.73

=(-79.73+79.73)+(79.27-73.27)

=27(79-73)

=27.6

=162

☕

bài này dễ lắm

a) 162

a, -79(73-27) - 73(-79+27)

= [-79.73 - (-79).27] - [73.(-79) + 73.27]

=-79.73 + 79.27 + 73.79 - 73.27

=79.27-73.27

=27(79-73)

=27.6= 162

b,   vì 2n luôn luôn là số chẵn với mọi n thuộc N nên 

=> 2n + 1 là số lẻ

ta có:

-5².13.(-2)².(-1)²ⁿ⁺¹

^{= -25.13.4.(-1)}

^{=25.13.4= 1300}

a)

=25 . 13 . 4. (-1) = 100.(-13)=-1300

b)

= -79.73 + 79.27 + 73. 79 - 73. 27

=79. 27 - 73. 27

=27. 6=162

\(\left(-12\right)+\left(-13\right)+36+\left(-11\right)=\left(-12-13-11\right)+36\)

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

                                                                         \(=0\)

\(111+\left(-11+27\right)=111-11+27\)

                                           \(=100+27\)

                                           \(=127\)

\(\left(27+514\right)-\left(486-73\right)=27+514-486+73\)

                                                            \(=\left(27+73\right)+\left(514-486\right)\)

                                                            \(=100+28\)

                                                            \(=128\)

a. 111 + (-11 + 27)

= 111 - 11 + 27

= 100 + 27

= 127

b. (27 + 514) - (486 - 73)

= 27 + 514 - 486 + 73

= (27 + 73) + (514 - 486)

= 100 + 28

= 128

c. (36 + 79) + (145 - 79 - 36)

= 36 + 79 + 145 - 79 - 36

= (36 - 36) + (79 - 79) + 145

= 0 + 0 + 145

= 145

a/ = 111+(-11)+27

tự tính

b/ 27+514 - 486+73

tự tính

c/ 36 + 79 + 145 - 79 - 36

tick mk nha bn 

a. 111 + ( -11 + 27 )

= 111 - 11 + 27

= 100 + 27

= 127

Câu b,  c làm tương tự

a: \(-7264+\left(1543+7264\right)\)

\(=-7264+1543+7264\)

\(=\left(-7264+7264\right)+1543\)

=0+1543

=1543

b: \(\left(144-97\right)-144\)

\(=144-97-144\)

\(=\left(144-144\right)-97\)

=0-97

=-97

c: \(\left(-145\right)-\left(18-145\right)\)

\(=-145-18+145\)

\(=\left(-145+145\right)-18\)

=0-18

=-18

d: \(111+\left(-11+27\right)\)

\(=\left(111-11\right)+27\)

=100+27

=127

e: \(\left(27+514\right)-\left(486-73\right)\)

\(=27+514-486+73\)

\(=\left(27+73\right)+\left(514-486\right)\)

\(=100+28=128\)

f: \(\left(36+79\right)+\left(145-79-36\right)\)

\(=36+79+145-79-36\)

\(=\left(36-36\right)+\left(79-79\right)+145\)

=0+0+145

=145

Ta có :

\(\frac{x-3}{97}+\frac{x-27}{73}+\frac{x-67}{33}+\frac{x-73}{27}=4\)

\(\Leftrightarrow\left(\frac{x-3}{97}-1\right)+\left(\frac{x-27}{73}-1\right)+\left(\frac{x-67}{33}-1\right)+\left(\frac{x-73}{27}-1\right)=0\)

\(\Leftrightarrow\frac{x-100}{97}+\frac{x-100}{73}+\frac{x-100}{33}+\frac{x-100}{27}=0\)

\(\Leftrightarrow\left(x-100\right)\left(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}\right)=0\)

Vì \(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}>0\) Nên \(x-100=0\)

\(\Leftrightarrow x=100\)

Vậy \(x=100\)

\(\Leftrightarrow\frac{x-3}{87}+\frac{x-27}{79}+\frac{x-67}{33}+\frac{x-73}{27}-4=0\)

\(\Leftrightarrow\left(\frac{x-3}{97}-1\right)+\left(\frac{x-27}{73}-1\right)+\left(\frac{x-67}{33}-1\right)+\left(\frac{x-73}{27}-1\right)=0\)

\(\Leftrightarrow\left(\frac{x-3-97}{97}\right)+\left(\frac{x-27-73}{73}\right)+\left(\frac{x-67-33}{33}\right)+\left(\frac{x-73-27}{27}\right)=0\)

\(\Leftrightarrow\frac{x-100}{97}+\frac{x-100}{73}+\frac{x-100}{33}+\frac{x-100}{27}=0\)

\(\Leftrightarrow\left(x-100\right)\left(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}\right)=0\)

Vì \(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}\ne0\)

\(\Rightarrow x-100=0\Leftrightarrow x=100\)

\(\frac{x-3}{97}+\frac{x-27}{73}+\frac{x-67}{33}+\frac{x-73}{27}=4\)    

\(\frac{x-3}{97}-1+\frac{x-27}{73}-1+\frac{x-67}{33}-1+\frac{x-73}{27}-1=4-1-1-1-1\)     

\(\frac{x-100}{97}+\frac{x-100}{73}+\frac{x-100}{33}+\frac{x-100}{27}=0\)    

\(\left(x-100\right)\left(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}\right)=0\)   

\(x-100=0\) 

\(x=100\)

Bài làm :

\(a,53.11+79.101\)

\(=583+7979\)

\(=8562\)

\(b,45.22+55.23\)

\(=9.5.11.2+55.23\)

\(=55.\left(18+23\right)\)

\(=55.41\)

\(=2255\)

\(c,27.332+68.27+73.332+68.73\)

\(=332.\left(27+73\right)+68.\left(27+73\right)\)

\(=\left(332+68\right).\left(27+73\right)\)

\(=400.100\)

\(=40000\)

Học tốt