Tong cua hai so la so co hai chu so giong nhau ma chu so hang chuc la 7,so hang thu nhat la 9.Vay so hang thu hai la bao nhieu
bai 1. 11/3.40/13+37/5:7/33-(11/13.1/3+33/7:5/2)
bai 2.tim x
a,3.(x-1)-5.(-7)=(-2)^3-2x
b,2./(1-x)^2+1/-2^2.3=8
bai 3,cho bieu thuc
M=n+1/n+1 - 3-8n/n+1 + 8/n+1
tim cac gia tri cua n de bieu thuc M co gia tri la so nguyen
bai 4,So hoc sinh cua 1 truong ko qua 1000 em,neuxeptoan bo so hoc sinh cua truong do thanh cac hang,moi hang 20 nguoi thi con thieu 5 nguoi,neu xep moi hang 25 nguoi hoac 30 nguoi thi deu thua 15 nguoi , neu xep 42 hang thi vua du . hoi truong do co bao nhieu hoc sinh
bai 5,cho bieu thuc
A=2+2^2+...+2^200
c/m rang
a, A+2 la 1 luy thua cua 2
b, Achia het cho 30
c,A co phai la so chinh phuong ko ? vi sao ?
bai 6,cho 2 bieu thuc
A=1/1+2 + 1/1+2+3 + ...1/1+2+3+...+99
B=1 + 1/2^2+1/3^2 + ...+1/49^2
c/m rang A<B
cho mot so tu nhien va mot so thap phan co tong bang 2032,11 .Bo dau phay cua so thap phan di thi tong se bang 4023 .Tim so thap phan do.Tra loi: So thap phan do la........
Cs co 2 chu so ,chuso hc chia het cho chu so hang don vi.Tim so da cho biet so do gap 21 lan thuong chu so hc va hdv
Cho day so 1 , 4 , 9 , 16 , 25 , ...........
a) Tim so hang thu 20 cua day so.
b) So 92 co phai la mot so hang cua day so do khong ?
Trong 1 lop 60% so hs gioi la 9 em
a)tinh so hs gioi cua lop
b)2/3 hs kha = 80% HSgioi. tim so hs kha cua lop
C)biet lop chi co gioi va kha. tim tong so hs cua lop
ai nhanh mk tick cho
giup mik cau nay voi:
Cho day so 2,7,14,23,34.Neu quy luat cua day so va cho biet so thu 234 cua day la so nao?
tim so co 3chu so biet rang chu so hang don vi bang 1 phan 5 chu so hang tram va bang 1phan 4 chu so hang chuc .
tinh tong :
a, \(\dfrac{1}{n}\) -\(\dfrac{1}{n+a}\) voi a;n la so tu nhien va n khac 0