Answer:
n(n+1)(n+5)/3
Step-by-step explanation:
there is no value, as we don't know n.
but we can create a summary formula/ function definition :
this is the sum for k = 1 to n of k×(k+3)
k×(k+3) = k² + 3k
so, the overall sum splits into the sum of k² for k=1 to n, and the sum of 3k for k=1 to n.
and the sum of 3k is 3 times the sum of k for k=1 to n.
Σk² for k=1 to n = [n(n+1)(2n+1)]/6
Σk for k=1 to n = n(n+1)/2
3×Σk for k=1 to n = 3×n(n+1)/2
so, we have a function formula
n(n+1)(2n+1)/6 + 3n(n+1)/2 = n(n+1)(2n+1)/6 + 9n(n+1)/6 =
= n(n+1)(2n+1+9)/6 = n(n+1)(2n+10)/6 = n(n+1)(n+5)/3
Answer:
180/45 = 4/1, he did 4 situps in 1 second.
Answer:
<h3>x = 1 and 2/3 or x = 1 2/3</h3><h3 />
Step-by-step explanation:
Simplify both sides of equation
1 * x = 1 2/3
1 * x is 1x which is the same as x because there is one x
then for the improper fraction which is 1 2/3
to simplify improper fractions we times the whole number by the denominator
so 1 * 3 then add the numerator 2 and the denominator stays the same so we get x = 5/3
now we have x = 5/3 this is not correct because the numerator is bigger than the denominator so we just subtract the denominator from the numerator and how many times 3 goes into 5 (in this case 1) becomes the new whole number.
therefore we get x = 1 2/3
Well, don't you already have the t value ,-7.
