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:
2 * 10^3 = 2000.
Step-by-step explanation:
3.8/1.9 * 10^5/10^2
= 2 * 10^3
15a-25=35
3.333
Leah needs to buy some apples from the grocery store. She places fifteen apples in her cart and proceeds to the checkout. Lucky for her, there happens to be a discount on apples for the day. She saves $25 on her purchase. The total money she ends up spending was only $35 (excluding tax). How much did each apple cost?
