Question

1,-2,3,-4,5... what’s the next two numbers in the pattern?

Answer 1

Answer:

The two numbers following 1,-2,3,-4,5...  are -6 and 7.

Step-by-step explanation:

index:   1   2   3   4   5 ....

value:    1  -2  3  -4   5

Let the index be n.  Then the first term is a(1), the secon is a(2), and so on.

a(2) = 2*(-1)^(2-1) = 2*(-1) = -2 (correct)

a(3) = 3*(-1)^(3-1)   =  3*(-1)^2 = 3 (correct)

a(4) = 4*(-1)^(4-1)    = 4*(-1)^3 = -4 (correct)

So the general formula for a(n)  is:    a(n)=n(-1)^(n-1)

Thus,

a(5) = 5(-1)^4 = 5

a(6) = 6(-1)^5 = -6

a(7) = 7(-1)^6 = 7

The "next two numbers in the pattern" are -6 and 7.  The first 7 numbers are

1,-2,3,-4,5, -6, 7