The sum of the 1st nth term gp is 127.the sum of the reciprocal is 127/64,if the 1st term is 1.find n and the common ratio

Ratio (r) = 2

n = 7

Step-by-step explanation:

The formula for the sum of the nth term of a G.P is given as:

Sn = a(1-r^n)/(1-r)

Where n = Number of terms

r = Common ratio

The sum of the 1st nth term gp is 127.

Hence:

127 = 1(1-r^n)/(1-r)

The sum of the reciprocal is 127/64

The formula is inverted , hence:

Sn = 1/a(1-r^n)/(1-r)

127/64 = r^(1-n)(1-r^n)/(1-r)

Hence:

1/64 = r^(1-n)

r^(n-1) = 64

r^(n-1) = 2⁶

Hence:

r = 2

Solving for n

n - 1 = 6

n = 6 + 1

n = 7

Therefore:

r = 2

n = 7

answer:   28.56 feet (approx)

step-by-step explanation:

since, triangle abc has measure of angle c equal to 55 degrees, measure of angle abc equal to 90 degrees, and length of bc equal to 20 feet.

we have to find out the measurement of segment ab.

therefore, tan 55° =

but bc = 20 feet.

⇒ tan 55 ° =  

⇒ ab = 20 × tan 55 °

⇒ ab = 20 × 1.42814800674

⇒ ab = 28.5629601348   ≈ 28.56 feet