3.03

làm tất cả nha

Sửa đề: \(P=2\cdot101+3\cdot100+4\cdot99+\cdots+99\cdot4+100\cdot3+101\cdot2\)

Ta có: \(P=2\cdot101+3\cdot100+4\cdot99+\cdots+99\cdot4+100\cdot3+101\cdot2\)

\(=2\left(2\cdot101+3\cdot100+4\cdot99+\cdots+51\cdot52\right)\)

\(=2\left\lbrack2\cdot\left(103-2\right)+3\left(103-3\right)+\cdots+51\left(103-51\right)\right\rbrack\)

\(=2\cdot\left\lbrack103\left(2+3+\cdots+51\right)-\left(2^2+3^2+\cdots+51^2\right)\right\rbrack\)

\(=2\cdot\left\lbrack103\cdot\left(51-2+1\right)\cdot\frac{\left(51+2\right)}{2}-\left(1^2+2^2+\cdots+51^2\right)+1^2\right\rbrack\)

\(=2\cdot\left\lbrack103\cdot50\cdot\frac{53}{2}-\frac{51\cdot\left(51+1\right)\left(2\cdot51+1\right)}{6}+1\right\rbrack\)

\(=2\cdot\left\lbrack103\cdot25\cdot53-\frac{51\cdot52\cdot103}{6}+1\right\rbrack=2\cdot\left\lbrack103\cdot25\cdot53-17\cdot26\cdot103+1\right\rbrack\)

=181900

Ta có: \(Q=2^2+3^2+\cdots+101^2\)

\(=1^2+2^2+3^2+\cdots+101^2-1\)

\(=101\left(101+1\right)\cdot\frac{\left(2\cdot101+1\right)}{6}-1=101\cdot102\cdot\frac{203}{6}-1\)

\(=101\cdot17\cdot203-1=348551-1=348550\)

P+Q

=181900+348550

=530450

C=1*2+2*3+3*4+...+98*99

C=2+6+12+...+9702

C=2+9702

C=9704

vay C=9704

D=(1*99+2*99+3*99+...+99*99)-(1*2+2*3+3*4+...+98*99)

D=(99+198+297+...+9801)-(2+6+12+...+9702)

D=(99+9801)-(2+9702)

D=9900-9704

D=196

vay D=196

ai di qua dong tinh thi nho h cho minh nhe

 \(M=1995^2-1994.1996\)       

     \(=1995^2-\left(1995-1\right)\left(1995+1\right)\)

     \(=1995^2-\left(1995^2-1\right)=1\)

\(N=9^8.2^8-\left(18^4-1\right)\left(18^4+1\right)\)

   \(=18^8-\left(18^8-1\right)=1\)

\(K=99^3+3.99^2+3.99+1\)

   \(=99^3+3.99^2.1+3.99.1^2+1^3\)

   \(=\left(99+1\right)^3\)

   \(=100^3=1000000\)

Chúc bạn học tốt.

Bài làm:

c) \(M=1995^2-1994.1996=1995^2-\left(1995-1\right)\left(19995+1\right)=1995^2-1995^2+1^2=1\)

d) \(N=9^8.2^8-\left(18^4-1\right)\left(18^4+1\right)=18^8-18^8+1^2=1\)

e) \(K=99^3+3.99^2+3.99+1=\left(99+1\right)^3=100^3=1000000\)

Học tốt!!!!!

( 0, 872 : 2,18 + 4,578 : 3,27 ) x 2,02 - 2,707 
= ( 0,4 + 1,4 ) x 2,02 - 2,707 
= 1,8 x 2,02 - 2,707 
= 3,636 - 2,707 
= 0,929

kề thiếu kìa

đáng ra phải nói có bao nhiêu số

chứ như vậy k làm đc đâu

sai de

A= 33333...333\(\times\)4

(50 chữ số 3)

hay đấy