Q. Find the 9th term of the geometric sequence shown below.7x3,−14x8,28x13,…Answer:
Identify common ratio: Identify the common ratio r of the geometric sequence by dividing the second term by the first term.Calculation: r=7x3−14x8r=−2x5
Verify consistency: Verify the common ratio by dividing the third term by the second term to ensure it is consistent.Calculation: r=−14x828x13r=−2x5
Use nth term formula: Use the formula for the nth term of a geometric sequence, which is an=a1⋅r(n−1), where a1 is the first term and n is the term number.Calculation: a9=7x3⋅(−2x5)(9−1)
Simplify exponent: Simplify the exponent in the formula.Calculation: a9=7x3×(−2x5)8
Calculate power: Calculate the power of the common ratio.Calculation: (−2x5)8=(−2)8×(x5)8(−2)8=256(x5)8=x40
Multiply first term: Multiply the first term by the power of the common ratio.Calculation: a9=7x3×256×x40
Combine x terms: Combine the x terms by adding the exponents.Calculation: a9=7×256×x(3+40)a9=7×256×x43
Multiply constants: Multiply the constants to find the 9th term.Calculation: a9=7×256×x43a9=1792×x43
More problems from Operations with rational exponents