Ai biết giúp mk

\(\left(-30\right)+\left(-29\right)+.......+48+49+50\)

=\(\left(\left(-30\right)+30\right)+\left(\left(-29\right)+29\right)+\left(\left(-1\right)+1\right)+31+32+....49+50\)

\(=31+32+..........+49+50\) = \(\left(31+49\right)\left(32+48\right)+..........\left(40+40\right)+50\)

\(\left(80.9\right)+50=720+50=770\)

\(\left(-30\right)+\left(-29\right)+.....+48+49+50\)

\(=\left[\left(-30\right)+30\right]+\left[\left(-29\right)+29\right]+.....+\left[1+\left(-1\right)\right]+31+32+.....+50\)\(=0+0+0+...+31+32+33+....+50\)

\(=\left(\dfrac{50-31}{1}+1\right):2\left(50+31\right)=810\)

Vậy....

a,(-2)+7+(-12)+17+...+(-52)+57

=[(-2)+7]+[(-12)+17]+...+[(-52)+57]

=5+5+5+...+5               có 6 số 5

=5.6

=30

b,(-30)+(-29)+...+48+49+50

=[(-30)+(-29)]+...+31+32+...+50

=0+0+...+31+32+...+50

=0+31+32+...+50

=810

a, (-2+7)+(-12+17)+...+(-52+57)

=5+5+...+5

=5.6=30

b,(-30)+(-29)+...48+49+50

=(-30+30)+(-29+29)+...+(-1+1)+0+31+32+...+50

=0+0+0+...+0+31+32+...+50

=20.(31+50)=20.81=1620

(-30) + (-29) + ... + 48 + 49 + 50

=> [ (-30) + (-29) + 31 + 32] + (33 + 34 + 35 + ... + 48 + 49 + 50)

=> 4 + ( 50 + 33 ) . 18 : 2

=> 4 + 747 = 751

ta có

a)[ (-2)+7] +[(-12)+17]+....+[(-52)+57]

= 5+5+5+...+5 có 6 số 5

=5x6

=30

b)(-30)+(-29)+....48+49+50

 =[(-30)+30] +....+31+32+...+50

=0+..+0+31+32+....+50

=0+31+32+..+50

=810

sai rồi bạn

phải là O3

a) ( - 30 ) + ( - 29 ) + ( - 28 ) + ... + 48 + 49 + 50

= [ ( - 30 ) + 30 ] + [ ( - 29 )  + 29 ] + [ ( - 28 ) + 28 ] + ..... + 48 + 49 + 50

= 0 + 0 + 0 + .... + 31 + 32 + 33 + 34 + 35 + 36 + 37 + 38 + 39 + 40 + 41 + 42 + 43 + 44 + 45 + 46 + 47 + 48 + 49 + 50

=  31 + 32 + 33 + 34 + 35 + 36 + 37 + 38 + 39 + 40 + 41 + 42 + 43 + 44 + 45 + 46 + 47 + 48 + 49 + 50

= ( 31 + 49 ) + ( 32 + 48 ) + ( 33 + 47 ) + ( 34 + 46 ) + ( 35 + 45 ) + ( 36 + 44 ) + ( 37 + 43 ) + ( 38 + 42 ) + ( 39 + 41 ) + 50

= 80 + 80 + 80 + 80 + 80 + 80 + 80 + 80 + 80 + 50

= 80 . 9 + 50

= 720 + 50

= 770

a)

uses crt;
var b:real;

i:integer;
begin
clrscr;
i:=10;
b:=1;
while i<=30 do
begin
b:=b*i;
i:=i+1;
end;
writeln('B=',b:0:0);

readln;

end.

b) uses crt;
var c,j:integer;
begin
clrscr;
j:=50;
c:=0;
while j<=100 do
begin
c:=c+j;
j:=j+1;
end;
writeln('C=',c);

readln;

end.

c) uses crt;

var i,d:integer;

begin

clrscr;

i:=-50;

d:=0;

while i<=50 do

begin

d:=d+i;

inc(i);

end;

writeln('D=',d);

readln;

end.

d) uses crt;

var n,i:integer;

e:real;

begin

clrscr;

write('n='); readln(n);

e:=0;

for i:=1 to n do

e:=e+1/(i*(i+2));

writeln('E=',e:4:2);

readln;

end.

đúng oy hình như sai đề

sai that roi day

A= -135

Ai thay dung thi k cho mik nha

\(\dfrac{7^{48}.5^{30}.2^8-5^{30}.7^{49}.2^{10}}{5^{29}.2^8.7^{48}}\)

\(=\dfrac{7^{48}.5^{29}.2^8\left(5-5.7.2^2\right)}{5^{29}.2^8.7^{48}}\)

\(=\dfrac{5-5.7.2^2}{1}\)

\(=5-140\)

\(=-135\)