Ta có: a2+b2+1≥ab+a+b
<=>2a2+2b2+2≥2ab+2a+2b
<=>(a2−2ab+b2)+(a2−2a+1)+(b2−2b+1)≥0
<=>(a−b)2+(a−1)2+(b−1)2≥0 ( Luôn đúng với V a,b)
Vậy a2+b2+1≥ab+a+b
Cho a1 , a2, a3 ... , a9 duoc xd boi cong thuc:
ak= 3k^2+3k+1/(k^2+k)^3 voi moi k lon hon hoac bang 1
tong 1+a1+a2+....+a9 co gia tri
giai bat phuong trinh thuong x mu hai cong 1 chia 3 tru x lon hon hoac bang khong
hop chat A co cong thuc phan tu la \(M_2X\). Tong so hat mang dien nhieu hon so hat ko mang dien la 116 , trong do tong so hat mang dien nheu hon tong so hat ko mang dien la 36 . Nguyen tu khoi cua X lon hon nguyen tu khoi cua M la 9 . Tong so hat trong nhuyen tu X nhieu hon tong so hat trong nguyen tu M la 14 . Xac dinh cong thuc phan tu cua A
cho cac so thuc x,y,z thoa man 0<a<hoac=x,y,z < hoac=b . tim gia tri lon nhat cua bieu thuc
T= I ab-xy I / (x+y)x + I bc-yz I / (y+z)x + Ica-zxI / (z+x)y
ai lam duoc cau nay minh cong nhan la gioi
cho abc=1 chung minh a tren ab+a+1 cong voi b tren bc+b+1 cong voi c tren ac +c+1
CMR so thuc a,b,c thi a^2+b^2+c^2+ab+bc+ca lon hon hoac bang 0
CMR so thuc a,b,c thi a^2+b^2+c^2+ab+bc+ca lon hon hoac bang 0
tong so cong nhan cua 2 cong truong xay dung đc là 300 sau khi chuyển 2 cong nhan cua cong truong 1 sang cong truong 2 thì 2/3 số cong nhan cua cong truong 1 =4/9 số cong nhan cua cong truong 2 hoi so cong nhan cua moi cong truong ban đầu
Hinh thang ABCD co AB//CD,goc A bang 3 lan goc D,goc B tru goc C bang 30 khi do goc A cong goc B bang?
