Tính −1+2−3+4−5+6++(−1)n∗n

Fred has a total of 62 dvd and cd. if the number of cd is three more than two times the number of dvd, how many cd does he have?

What is the probability of throwing several dice with sum equal to 6 (six)? show the ways of possibilities for sum 6 (as the numerator) and the ways of throwing n dices for n = 1, 2, 3, 4 or 5 as denominator for all the questions to earn full credits. (a)throw one die, (b) throw two dice, (c) throw three dice (d) throw 4 dice, (e) throw 5 dice

One side of a rectangle is 7 centimeters shorter than six times the other side. find the length of the longer side if we also know that the perimeter of the rectangle is 266 centimeters.