Because like terms you add or subtract together to make it easier to do the problem. just like you do with whole numbers. you add an subtract to make the answer simpler.
The large box is less expensive per ounce.
large box small box
cost 4.16 2.38
content 32oz 14oz
cost/oz 0.13 0.17
*4.16/32 *2.38/14
The large box is less expensive than the small box. The large box is cheaper by 0.04 per ounce.
Answers:
The series converges
The sum is -8/3
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a = -4 is the first term
r = -1/2 is the common ratio
the reason why is because the expression -4(-1/2)^(n-1) is in the form a(r)^(n-1). Notice how -4 matches with the 'a'; the -1/2 matches with the r
The common ratio will determine if the infinite series converges or not.
r = -1/2 leads to |r| = |-1/2| = 1/2 = 0.5
Since |r| < 1 (in this case 0.5 < 1) is true, this means the series does converge.
Put another way, because r = -1/2 = -0.5 makes -1 < r < 1 true, the series converges.
Use the formula below to find the converging value S
S = a/(1-r)
S = -4/(1-(-1/2))
S = -4/(1+1/2)
S = -4/(2/2+1/2)
S = -4/(3/2)
S = (-4/1)/(3/2)
S = (-4/1)*(2/3)
S = (-4*2)/(1*3)
S = -8/3
The infinite series converges to -8/3
So the sum is -8/3
