Question

Question #39a8d

Answer 1

The answer is 108.

Explanation:

`x_2+x_4=104`
`x_2-x_4=40`

so, adding member to member the two equations:

`2x_2=144rArrx_2=72`

and

`x_4=72-40=32`.

The geometric sequence is a sequence in which the ratio between two consecutive numbers is constant (`=q`).

So:

`x_4=x_3*q=(x_2*q)*q=x_2*q^2`,

then:

`q^2=x_4/x_2=32/72=4/9rArrq=2/3`, (`q` is a positive number!)

and:

`x_2=x_1*qrArrx_1=x_2/q=72*3/2=108`.