Answer:
D. 119
Step-by-step explanation:
To find the common difference, we take the second term and subtract the first term
2-(-7) = 9
We check by taking the third term and subtracting the second
11-2 = 9
The common difference is 9
The formula for an arithmetic sequence is
an = a1 +d(n-1)
where a1 is the first term, d is the common difference and n is the number of the term in the sequence
a1=-7, d=9 and we are looking for the 15th term so n=15
a15 = -7 +9(15-1)
a15 = -7+9(14)
=-7 +126
= 119
Answer:
4-9=-5
Step-by-step explanation:
do the work you get that
Let x and y be the 2 parts of 15 ==> x + y=15 (given)
Reciprocal of x and y ==> 1/x +1/y ==> 1/x + 1/y = 3/10 (given)
Let's solve 1/x + 1/y = 3/10 . Common denominator = 10.x.y (reduce to same denominator)
==> (10y+10x)/10xy = 3xy/10xy ==> 10x+10y =3xy
But x+y = 15 , then 10x+10y =150 ==> 150=3xy and xy = 50
Now we have the sum S of the 2 parts that is S = 15 and
their Product = xy =50
Let's use the quadratic equation for S and P==> X² -SX +P =0
Or X² - 15X + 50=0, Solve for X & you will find:
The 1st part of 15 is 10 & the 2nd part is 5
