Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Find an explicit formula for the geometric sequence

-25,-50,-100,-200,dots". "
Note: the first term should be d(1).

d(n)=

Find an explicit formula for the geometric sequence\newline25,50,100,200,-25,-50,-100,-200,\dots. \newlineNote: the first term should be d(1)d(1).\newlined(n)=d(n)=

Full solution

Q. Find an explicit formula for the geometric sequence\newline25,50,100,200,-25,-50,-100,-200,\dots. \newlineNote: the first term should be d(1)d(1).\newlined(n)=d(n)=
  1. Identify Terms and Ratio: We need to identify the first term a1a_1 and the common ratio rr of the geometric sequence.\newlineThe first term a1a_1 is given as 25-25.\newlineTo find the common ratio rr, we divide the second term by the first term.\newliner=(50)/(25)=2r = (-50) / (-25) = 2
  2. Calculate Common Ratio: Now that we have the first term a1a_1 and the common ratio rr, we can write the explicit formula for the nnth term of a geometric sequence, which is:\newlined(n)=a1r(n1)d(n) = a_1 \cdot r^{(n-1)}\newlineSubstitute a1=25a_1 = -25 and r=2r = 2 into the formula.\newlined(n)=252(n1)d(n) = -25 \cdot 2^{(n-1)}
  3. Write Explicit Formula: Let's perform a quick check to ensure that our formula is correct by plugging in n=1n=1 to see if we get the first term of the sequence.d(1)=25×2(11)=25×20=25×1=25d(1) = -25 \times 2^{(1-1)} = -25 \times 2^0 = -25 \times 1 = -25This matches the first term of the sequence, so our formula appears to be correct.

More problems from Write variable expressions for arithmetic sequences