Answer:
see below
Step-by-step explanation:
The formula for the sum of an infinite geometric series with first term a1 and common ratio r (where |r| < 1) is ...
sum = a1/(1 -r)
Applying this to the given series, we get ...
a. sum = 5/(1 -3/4) = 5/(1/4) = 20
b. sum = d/(1 -1/t) = d/((t-1)/t) = dt/(t-1)
_____
The derivation of the above formula is in most texts on sequences and series. In general, you write an expression for the difference of the sum (S) and the product r·S. You find all terms of the series cancel except the first and last, and the last goes to zero in the limit, because r^∞ → 0 for |r| < 1. Hence you get ...
S -rS = a1
S = a1/(1 -r)
Answer:
combined variation
Step-by-step explanation:
we have

we know that
a)<u> in the interval </u>----> (0,∞)
If the value of x increase the value of y increase
so
Is a direct variation
b) <u>in the interval -</u>---> (-∞,0)
If the value of x increase the value of y decrease
so
Is a inverse variation
therefore
Is a combined variation
Answer is D
Step by step explanation
Make it into a simultaneous equation:
5p + 4e = 7.65
4p + 5e = 7.20
Use adding/subtracting formula
The cost of an eraser is $1.44