\(C=1-4+7-10+...+3001-3004\)

\(\Rightarrow C=\left(1-4\right)+\left(7-10\right)+...+\left(3001-3004\right)\)

\(\Rightarrow C=\left(-3\right)+\left(-3\right)+...+\left(-3\right)\)

Có 501 số -3

\(\Rightarrow C=\left(-3\right).501\)

\(\Rightarrow C=-1503\)

\(A=2219.2221.2226-2218.2223.2225\)

\(A=2219.(2223-2).2226-2218.2223.2225\)

\(A=2219.2223.2226-2.2219.2226-2218.2223.2225\)

\(A=2223.(2219.2216-2218.2225)-2.2219.2216\)

\(A=2223.\left\{(2218+1).(2215+1)-2218.2225\right\}-2.2219.2216\)

\(A=2223.(2218+2225+1)-2219.2226-2219.2226\)

\(A=2223.2219+2223.2225-2219.2226-2219.2226\)

\(A=(2223.2219-2219.2226)+2223.2225-2219.2225-2219\)

\(A=2219.(-3)+2225.4-2219\)

\(A=2219.(-4)+2225.4\)

\(A=4.(2225-2219)\)

\(A=4.6\)

\(A=24\)

\(B=3004.2999.2997-3003.2996.3001\)

\(B=3004.2999.(3001-4)-3003.2996.3001\)

\(B=(3003+1).2999.3001-3004.2999.4-3003.2996.3001\)

\(B=3003.(2996+3).3001+2999.3001-3004.2999.4-3003.2996.3001\)

\(B=3003.2996.3001+3.3003.3001-3.3004.2999+2999.3001-3004.2999-3003.2996.3001\)

\(B=3.(3003.3001-3004.2999)+2999.(3001-3004)\)

\(B=3.\left\{\left(3004-1\right).\left(2999+2\right)-3004.2999\right\}-3.2999\)

\(B=3.\left(3004.2999+2.3004-2999-2-3004.2999\right)-3.2999\)

\(B=3.(2.3003-2999)-3.2999\)

\(B=6.3003-6.2999\)

\(B=6.(3003-2999)\)

\(B=6.4\)

\(B=24\)

Mà \(A=24\) , \(B=24\)

\(\Rightarrow A=B\)

A=2219*(2223-2)*2226 - 2218*2223*2225

=2219*2223*2226 - 2*2219*2226 - 2218*2223*2225

=2223*(2219*2226 - 2218*2225) - 2*2219*2226

=2223*[(2218+1)*(2225+1) - 2218*2225] - 2*2219*2226

=2223*(2218+2215+1) - 2*2219*2226

=2223*2219+2223*2225 - 2219*2226 - 2219*2226

=(2223*2219 - 2219*2226) +2223*2225 - 2219*2225 - 2219

=2219*(-3) + 2225*4 - 2219

=2219*(-4) + 2225*4 = 4*(2225-2219) = 4*6 = 24

B=3004*2999*(3001-4) - 3003*2996*3001

=(3003+1)*2999*3001 - 3004*2999*4 - 3003*2996*3001

=3003*(2996+3)*3001 +2999*3001 - 3004*2999*4 - 3003*2996*3001

=3003*2996*3001+3*3003*3001 +2999*3001 - 3*3004*2999 - 3004*2999 - 3003*2996*3001

=3*(3003*3001 - 3004*2999) + 2999*(3001-3004)

=3*[(3004-1)*(2999+2) - 3004*2999] - 3*2999

=3*(3004*2999+2*3004 - 2999 - 2 - 3004*2999) - 3*2999

=3*(2*3003-2999) - 3*2999

=6*3003 - 6*2999 = 6*(3003-2999) = 6*4 = 24

===> A=B (=24)

1-4+7-10-2998+3001

=-3+7-10-2998+3001

=4-10-2998+3001

=-6-2998+3001

=-3004+3001

=3

bước cuối cùng phải là -3004+3001=-3 

\(A=1-4+7-10+...+2995-2998+3001\)

\(A=1+3+3+...+3+3\)

Từ 4\(\rightarrow\)3001 có: \(\left(3001-4\right):3+1=1000\)

Tổng từ \(1\)\(\rightarrow3001\): \(1+3.1000=3001\)

Vậy \(A=3001\)

h: =7000-6000

=1000

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