Respuesta :
Answer:
x = 8
Step-by-step explanation:
This sequence is a geometric sequence.
As it is a geometric sequence, It means that each term multiply by a value that we call that value "a".
So (x-4) × a = (x + 2)
Therefore [tex]\frac{x+2}{x-4} = a[/tex]
And (x+2) × a = (3x+1)
Therefore [tex]\frac{3x+1}{x+2} =a[/tex].
By this we can make a conclusion that [tex]\frac{3x+1}{x+2} =\frac{x+2}{x-4}[/tex].
- [tex]\frac{3x+1}{x+2}= \frac{x+2}{x-4}[/tex]
- [tex](3x + 1) * (x-4) = (x+2) * (x+2)[/tex]
- [tex]3x^{2} -11x-4=x^{2} +4x+4[/tex]
- [tex]2x^{2} -15x-8 = 0[/tex]
- [tex](2x+1) * (x-8) = 0[/tex]
In the last part one of the parentheses should be 0.
First we put (2x+1) equal to 0.
- [tex]2x+1 = 0[/tex]
- [tex]2x = -1[/tex]
- [tex]x = -\frac{1}{2}[/tex]
It gives us a negative answer, so this is not our answer.
Now we put (x-8) equal to 0.
- [tex]x-8=0[/tex]
- [tex]x = 8[/tex]
This is a positive answer and it is correct.
and the terms are 4, 10, 25 , ...
Please choose my answer as the brainliest answer.
Answer:
- 4, 10, 25, 62.5, ...
Step-by-step explanation:
Given GP:
- x - 4, x + 2, 3x + 1, ...
Common ratio is:
- (x + 2)/(x - 4) = (3x + 1)/(x + 2)
Cross-multiply and solve for positive x:
- (x + 2)² = (x - 4)(3x + 1)
- x² + 4x + 4 = 3x² - 11x - 4
- 2x² - 15x - 8 = 0
- x = (15 + √(15² + 4*2*8))/4
- x = (15 + 17)/4
- x = 8
The first term is:
- 8 - 4 = 4
The common ratio is:
- (8 + 2)/4 = 2.5
The nth term is:
- aₙ = 4*(2.5)ⁿ ⁻ ¹
The sequence is:
- 4, 10, 25, 62.5, ...