Respuesta :
Given:
[tex]x = 1, y = 7,z = 15[/tex]
A number is added to x, y, and z yields consecutive terms of a geometric sequence.
To find:
The number which is added to x, y, and z, then find the first three terms in the geometric sequence.
Solution:
Let the unknown number be k.
After adding k to x, y, and z, we get
[tex]x = 1+k, y = 7+k,z = 15+k[/tex]
These are the consecutive terms of a geometric sequence. So,
[tex](7+k)^2=(1+k)(15+k)[/tex]
[tex]49+14k+k^2=15+k+15k+k^2[/tex]
[tex]49+14k=15+16k[/tex]
Isolate the variable terms.
[tex]49-15=16k-14k[/tex]
[tex]34=2k[/tex]
[tex]\dfrac{34}{2}=k[/tex]
[tex]17=k[/tex]
The unknown number is 17.
Now,
[tex]x=1+k[/tex]
[tex]x=1+17[/tex]
[tex]x=18[/tex]
Similarly,
[tex]y=7+k[/tex]
[tex]y=7+17[/tex]
[tex]y=24[/tex]
And
[tex]z=15+k[/tex]
[tex]z=15+17[/tex]
[tex]z=32[/tex]
Therefore, the three terms in the geometric sequence are 18, 24, 32.
