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In a geometric sequence, the first term, 
a_(1), is equal to 1 , and the third term, 
a_(3), is equal to 36 . Which number represents the common ratio of the geometric sequence?

r=3

r=4

r=5

r=6

In a geometric sequence, the first term, a1 a_{1} , is equal to 11 , and the third term, a3 a_{3} , is equal to 3636 . Which number represents the common ratio of the geometric sequence?\newliner=3 r=3 \newliner=4 r=4 \newliner=5 r=5 \newliner=6 r=6

Full solution

Q. In a geometric sequence, the first term, a1 a_{1} , is equal to 11 , and the third term, a3 a_{3} , is equal to 3636 . Which number represents the common ratio of the geometric sequence?\newliner=3 r=3 \newliner=4 r=4 \newliner=5 r=5 \newliner=6 r=6
  1. Identify Given Terms: Identify the given terms in the geometric sequence.\newlineWe are given the first term a1a_{1} and the third term a3a_{3} of the geometric sequence. The first term is 11 a1=1a_{1} = 1 and the third term is 3636 a3=36a_{3} = 36.
  2. Write nth Term Formula: Write the formula for the nth term of a geometric sequence.\newlineThe nth term of a geometric sequence is given by an=a1r(n1)a_n = a_1 \cdot r^{(n-1)}, where a1a_1 is the first term and rr is the common ratio.
  3. Express Third Term: Use the formula to express the third term in terms of the first term and the common ratio.\newlineWe have a3=a1r31=a1r2a_{3} = a_{1} \cdot r^{3-1} = a_{1} \cdot r^2.
  4. Substitute Given Values: Substitute the given values into the equation.\newlineWe know that a1=1a_{1} = 1 and a3=36a_{3} = 36, so we can write 36=1×r236 = 1 \times r^{2}.
  5. Solve for Common Ratio: Solve for the common ratio rr. To find rr, we take the square root of both sides of the equation: r2=36r^2 = 36, so r=±36r = \pm\sqrt{36}.
  6. Determine Positive Ratio: Determine the positive value of the common ratio.\newlineSince a common ratio in a geometric sequence is typically positive, we take the positive square root of 3636, which is 66. Therefore, r=6r = 6.

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