cho n bong den mac noi tiep vao nguon co U=40v.loai 1 co hieu dien the 2 dau moi bong la U1=3v. loai 2 co hieu dien the 2 dau moi bong la U2=5v. tim n
tim stn n nho nhat de co bat dang thuc (a^2+b^2+c^2)^2=n(a^4+b^4+c^4)
TIm so lon nhat, nho nhat co 9 chu so biet so do chia 5,7,9,11 co so du lan luot la 3,4,5,6
cho duong tron (O) co BC la day cung co dinh nho hon duong kinh , A la diem di dong tren cung BC lon ( A khong trung B va C). goi AD, BE, CF la duong cao cua tam giac ABC, EF cat BC tai M. Qua D ke duong thang song song EF cat AB tai P va cat AC tai Q:
a) CM: \(\widehat{BPQ}=\widehat{BCQ}\)va tu giac BPCQ noi tiep
b) CM: tam giac DPF can tai D
c) goi N la trung diem BC. CM: MF.ME=MD.MN
d) CM duong tron ngoai tiep tam giac MPQ luon di qua 1 diem co dinh khi A di dong tren cung lon BC
1> voi gia tri nao cua so tu nhien a thi 5a-17 tren 4a-23 co gia tri lon nhat
Cho 2 hinh chu nhat co cung dien tich .HInh 1 co kich thuoc a va b (a lon hon b) hinh 2 co kich thuoc c va d (c lon hon d) .chung minh rang nêu a lon hon c thi chu vi cua hinh1 lon hon chu vi hinh 2
Cho m, n thuoc N va m+n=S. Tim m, n de m*n lon nhat
cho phuong trinh x2+(2m-5)x-n=0 cho m=5 tim n nguyen nho nhat de bphuong trinh co nghiem duong
Mot cai san hinh chu nhat co chieu dai 12cm, rong 8cm. Nguoi ta dung cac vien gach vuong co canh 20cm de lat nen
a) Tinh so vien gach can dung
b) Neu moi met vuong gach co gia 95 nghin dong thi lat het cai san do het bao nhieu tien