Short Answer D
P(1) = 1(1+1)(2*1 + 1)/6
P(1) = 1(2)(2 +1) / 6
P(1) = 1(2)(3)/6
P(1) = 1
P(2) = 2(2+1)(2*2 + 1) / 6
P(2) = 2(3)(5) / 6
P(2) = 5 So this formula is adding as it goes along. To Find the Total all we need do is use the formula to calculate P(1) to P(7)
P(7) = 7*(7 + 1)(2*7 + 1)/6
P(7) = 7 * 8 * 15 / 6
P(7) = 7 * 4 * 5
P(7) = 140 <<<< Answer
60-12-18-2-8=20
=48-18-2-8
=30-2-8
=28-8
=20
So, 20 students don't take either of these subjects.
Involving the second and no higher power of an unknown quantity or variable.
