Answer:
270
Step-by-step explanation:
For any arithmetic sequence
nth term is given by
nth term = a + (n-1)d
where a is first term,
d is common difference
d is given by nth term - (n-1)th term
sum of n terms given by
sum = n/2(2a + (n-1)d)
________________________________________________
Given arithmetic sequence
-2,0,2,4,6,8...
first term a = -2
lets take third term as nth term and second term as (n-1)th term to find common difference d.
d = 2 - 0 = 2
using a = -2 , d = 2, n = 18
thus, sum of first 18 terms = n/2(2a + (n-1)d)
=18/2( 2*(-2) + (18-1) 2)
=9 ( -4 + 34)
=9 ( 30) = 270
Thus, sum of first 18 terms is 270.
Answer:
i think it is the 2nd option tell me if i am wrong
Step-by-step explanation:
it seems the most logical answer
Answer:
25 percent discount
Step-by-step explanation:
40 x 0.25 gives you 10 and then you subtract from the orginal price
Answer: (3,1)
Step-by-step explanation:
2x + 3y = 9
(x + 5y = 8) -2
2x + 3y = 9
-2x - 10y = -16
-7y = -7
y = 1
2x + 3(1) = 9
2x = 6
x = 3
f(5) means that x=5
Now, we solve 5x-3 because we know what x is.
5(5)-3
25-3
22
F(5)=22
