Find a formula for the sum of the first n even positive integers.
1 answer:
So even postive integers are by defention in form 2k where k is a natural number so
let the sum of even integers to n=S
S=2(1+2+3+4+5+6+7+8+......+k-1+k
divide bith sides of equation 1 by 2
0.5S=1+2+3+4+5+...........+k-1+k
S=2(k+(k-1)+..............................+2+1)
divide both sides of equation 2 by 2
0.5S=k+k-1+..............................+2+1)
by adding both we will get
___________________________
S=(k+1)(k)
so the sum will be equal to
S=
so let us test the equation
for the first 3 even number there sums will be
2+4+6=12
by our equation 3^2+3=12
gave us the same answer so our equation is correct
let the sum of even integers to n=S
S=2(1+2+3+4+5+6+7+8+......+k-1+k
divide bith sides of equation 1 by 2
0.5S=1+2+3+4+5+...........+k-1+k
S=2(k+(k-1)+..............................+2+1)
divide both sides of equation 2 by 2
0.5S=k+k-1+..............................+2+1)
by adding both we will get
___________________________
S=(k+1)(k)
so the sum will be equal to
S=
so let us test the equation
for the first 3 even number there sums will be
2+4+6=12
by our equation 3^2+3=12
gave us the same answer so our equation is correct
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Answer:
The expression to determine the total cost in dollars is .
Step-by-step explanation:
Given:
Service charge to make a photo book = $20
Cost per extra page = $0.75
Cost to ship the complete photo book = $5
We need to write expression to determine the total cost in dollars.
Solution:
Let the number of extra pages be denoted by 'x'.
Also Let the Total cost be denoted by 'y'.
Now we can say that;
Total cost will be equal to sum of Service charge to make a photo book and Cost per extra page multiplied by number of extra pages and Cost to ship the complete photo book.
framing in equation form we get;
Hence the expression to determine the total cost in dollars is .