Các câu hỏi tương tự
a, Neu A la con cua B thi voi moi x thuoc a, ta co x thuoc B
b, De chung to A la con cua B ta phai chung to voi noi X thuoc A thi X thuoc B
c, quy uoc tap hop rong la tap hop con cua moi tap hop
d,de chung to a khong phai tap hop con cua b, chi can neu ra 1 phan tu thuoc a ma khong thuoc b
Cho a/b =c/d. CMR :
a) a+c/b+d = a-c/b-d.
b) a-b/b = c-d/d.
Ai biet thi chi giup minh voi nhe. Minh dang can gap lam.
Cho 4 điểm A,B,C,D thang hang . Biet do Đại cac doan thang AB bang 3cm , AC bang 6cm , AD bang10cm ( thu tu ABCD tu trai qua phai )
a) diem B co phai la truong diem cua Dian thang AC khong ? Vi sao
b) trong 3 diem B,C,D diem nao nam giua 2 diem con lai
ket qua nao sau day khong bang 2^4.4^2 a:2^8;b:16^2;c:8^2;d:4^4
cho tam giac ABC co BC=4cm. tren tia doi cua tia BC lay diem D sao cho BD=2cm/ a, tinh do dai CD; b,goi M la chung diem cua CD.tinh do dai BM;c,biet goc DAC bang 112 do .Ãxtia phan giac cua goc BAC va goc BAD. tinh so do goc xAy;d, tren nua mat phang bo la duong thang AC co chua diem D neu ve them n tia goc A phan biet khong trung voi cac tia ÂC,Ã,AB,Ay,AD thi co tat ca bao nhieu goc dinh A va Ay thu tu la
chung minh rang
a tong cua 3 so chan lien tiep thi chia het cho 6
b tong cua 3 so le lien tiep khong chia het cho 6
c neu a chia het cho b va b chia het cho c thi a chia het cho c
d neu a va b chia het cho 7 co cung so du thi hieu a-b chia het cho 7
Cho hai phan so bang nhau a/b=c/d.Chung to rang:
a)a+b/b = c+d/b
b)a-b/b=c-d/d
c)a/a+b=c/c+d
d)a/a-b=c/c-d
giup minh cau nay voi:Tim cac so tu nhien a,b,c,d nho nhat sao cho a/b bang voi3/5,b/c bang 12/21,c/d bang 6/11
cho 2 p/s a/b vs c/d (a,b,c,d la cac so nguyen duong ) chung minh rang neu a/b < c/d thi b/a > d/c