\(\Rightarrow3S=1.2.3+2.3.3+3.4.3+......+39.40.3\)\(.3\)
\(\Rightarrow3S=1.2.3+2.3.\left(4-1\right)+...+39.40.\left(41-38\right)\)
\(\Rightarrow3S=1.2.3+2.3.4-1.2.3+.....+39.40.41-38.39.40\)
\(\Rightarrow3S=39.40.41\)
\(\Rightarrow S=\frac{39.40.41}{3}\)
\(\Rightarrow S=21320\)
tnh bang cach hop li neu co the
1/2*3 +1/3.4 + 1/4*5 + ..... + 1/39*40
giup minh voi nhe mai phai nop rui
Chung minh: Co 3 so chinh phuong se luon co 2 so co hieu chia het cho 4
Giup minh nhanh nhe, minh cho 3 tk!
Tìm x là stn
6x : 33 :4 = 2
3.(x-5)3=81
7x - 2x=617: 615+ 38 : 26
Giup minh vơi a , co cach lam nhe a
Cam on
Tinh:
e.-13*|x|=39
f.-2+-3*|x|=10
Giup minh nhe!
bai 1 :
1) ( -213) + 186 + ( - 14 ) + 217 + 54 + ( - 49 )
2 ) - 38 . ( 25 - 4 ) + 25 . ( -4 + 38 )
3) -39 . ( 5 - 99 ) + 99 . ( 10 - 39 )
4 ) 1+ 3-5-7+9+ 11 - ....- 397 - 399
5) 1+ 2 + 2^2 + ... + 2 ^ 100
6) 3^102 - 3 ^ 100 - 3 ^ 98 -...3 ^2 - 3 ^0
cam phien cac ban lam giup minh nha
Chung minh : 19^93 -19^39 chia het cho 18
giup minh nhe ,neu lam bai thi co ca trinh bay nua nhe, can on cac ban
1.tim cs a de aaaaa24 (voi a la cs ) chia het cho 8 va 9
2.tong ket dot thi dua lop 6a co bon ba ban duoc tu 1 diem muoi tro len , 39 ban duoc tu hai diem muoi tro len muoi bon ban duoc tu 3 diem 10 tro len khong co ai duoc bon diem muoi tinh xem trong dot thi dua do 6a co bao nhieu diem 10
cac ban dua cau tra loi giup minh nhe minh can gap
S=1/2+1/3+...+1/38+1/39,P=1/39+2/38+...+38/2+39/1 tính S/P
Tinh nhanh :
1^2 +2^2 +3^2 +...+100^2
Giup minh voi nhe
