Problem with arithmetic sequence question (1 Viewer)

[dv3]

Im having trouble figuring this question out:

Question:

The first three terms of an arithmetic sequence are 7, x, 35. Find x

 

[flon]

x-7=35-x

2x=42

x=21

 

[addikaye03]

to further explain the above: they give u the fact that its arithmetic, a sequence is arithmetic if T3-T2=T2-T1, therefore use that to solve for x.

If geometric, T2/T1=T3/T2, same deal

 

[dv3]

x-7=35-x

I dont quite get the first bit???

2x=42

x=21

I get this bit but not the first bit i mentioned above

to further explain the above: they give u the fact that its arithmetic, a sequence is arithmetic if T3-T2=T2-T1, therefore use that to solve for x.

If geometric, T2/T1=T3/T2, same deal

btw thanks addikaye03 and flon for helping out

 

[addikaye03]

OP: "thanks addikaye03"
Addikaye03: "no worries man", thanks for the rep also"

Fair enuf...

 

[flon]

Anytime

 

[addikaye03]

flon, you did fuck all, all of a sudden your willing to help others with your unexplained answers, although the path to answering to Q was obvious, explain your answers.