Answer:
See below.
Step-by-step explanation:
I will assume that 3n is the last term.
First let n = k, then:
Sum ( k terms) = 7k^2 + 3k
Now, the sum of k+1 terms = 7k^2 + 3k + (k+1) th term
= 7k^2 + 3k + 14(k + 1) - 4
= 7k^2 + 17k + 10
Now 7(k + 1)^2 = 7k^2 +14 k + 7 so
7k^2 + 17k + 10
= 7(k + 1)^2 + 3k + 3
= 7(k + 1)^2 + 3(k + 1)
Which is the formula for the Sum of k terms with the k replaced by k + 1.
Therefore we can say if the sum formula is true for k terms then it is also true for (k + 1) terms.
But the formula is true for 1 term because 7(1)^2 + 3(1) = 10 .
So it must also be true for all subsequent( 2,3 etc) terms.
This completes the proof.
Answer:
Step-by-step explanation:
5
Answer:
The sides are
6
inches,
8
inches and
10
inches
Explanation:
I'd suggest that the question should read 'The perimeter of a triangle is 24 inches. The longest side is 4 inches longer than the shortest side, and the shortest side is three-fourths the length of the middle side. How do you find the length of each side of the triangle?'
In this case the question can be answered. If
x
is the length of the middle side, then the shortest side is 3/4x and the longest side is 3/4x+4
x+3/4x+3/4x+4=24
10/4x=20
x=8
Then the shortest side is 6and the longest side is 10
Step-by-step explanation:
Assume that
a and b = the two legs of the right triangle.
c = the hypotenuse.
The area of the right triangle is 750 yd², therefore
(1/2)*a*b = 750
ab = 1500 (1)
The perimeter is 150yd, therefore
a + b + c = 150 (2)
Let the side fenced with wood be a, at $5/yd. Sides b and c are fenced with steel at $10/y. The total cost is $1200, therefore
5a + 10b + 10c = 1200
or
a + 2b + 2c = 240 (3)
From (2), obtain
c = 150 - a - b (4)
Substitute (4) into (3)
a + 2b + 2(150 - a - b) = 240
-a + 300 = 240
a = 60
From (1), obtain
60b = 1500
b = 25
From (4), obtain
c = 150 - 60 - 25 = 65
Answer:
A. The length of the leg fenced with wood is 60 yd.
B. The length of the leg fenced with steel is 25 yd.
Answer:
The snowiest city receive 347.7 inches on average each year.
Step-by-step explanation:
We want to find the amount of snow the snowiest city receives on average every year, "x". It is known that this city receives 113.9 more inches than the second snowiest, which receives 223.8 inches on average every year. Therefore, the expression for "x" is:
The snowiest city receive 347.7 inches on average each year.
