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.
21 because you have to have at least 1 side as 3m so the other two should be 9m to have the greatest possible length
Answer:
Carry
Step-by-step explanation:
Here let’s take any arbitrary value for the number of properties sold by Ellen.
Let the number of properties sold by Ellen he 10. We were told Andy sold twice of this, this means he sold 20 properties
Bob sold 3 more than Ellen, meaning he sold 13.
Carry sold twice of Bob meaning he sold 26
Dora sold the addition of Bob and Ellen = 13 + 10 = 23
Carry sold 26 and this makes him the highest seller.
<span>speed = distance/time
total time is 8 hours
outgoing speed is 160 km per hour,
so time = d/160
</span><span>returning speed is 240 km per hour,
so time = d/240
d/160 + d/240 = 8
3d/480 + 2d/480 = 8
5d/480 = 8
5d =480 (8)
5d = 3840
d=3840/5
d=768
answer: so the distance is 768 km</span>
