tong tren co so cac so hang la:(100-2):2+1=50(so hang)
tong tren co so cap la:50:2=25cap
ta co:
-2+4-6+8-................-98+100
=(-2+4)+(-6+8)+........+(-98+100)
=2+2+..............+2(25 số 2)
=2.25=50
tính
B=2*4*6+4*6*8+6*8*10+...+94*96*98+96*98*100
A=1-2-3-4=5-6-7-8+9-10-11-12+...+97-98-99-100
B=1+2-3-4+5+6-7-8+....+97+98-99-100
E=-2+4-6+8-...-98+100
2+4+6+8+...+96+98+100
2 .4 + 4 . 6 + 6 . 8 + ... + 98 . 100 + 100 . 101
Giải nhanh giúp mình nha...!!!!!!
Tính:
B = 2 . 4 + 4 . 6 + 6 . 8 + ... + 98 . 100
2+4+6+8......98+100
2 - 4 + 6 - 8 + ................. + 98 - 100=?????
2+4+6+8....+98+100=???
