Answer:
495
Step-by-step explanation:
In order to find the sum of the first 18 terms you have to find the 18th term and the first term using the equation given.
a1=3(1)-1 a1=2
a18=3(18)-1 a18= 53
Then plug in 53 for an, 18 for n, and 2 in for a1 in the sum equation: Sn=n/2(a1+an)
Sn=18/2(2+53) Solve for sn= 495
Hello from MrBillDoesMath!
Answer:
11
Discussion:
Let "n" be the smaller number. Then
n * (n+5) = 176.
My first reaction to this problem was to factor 176 in my head. That's 176 = 16 * 11 and 16 is 5 more than 11. So that's the solution!.... Now let's solve it using the brute force approach:
n(n+5) = 176 =>
n^2 + 5n - 176 = 0 => use the quadratic formula
n = ( -5 +\- sqrt( 5^2 - 4(1)(-176)) ) /2
= ( -5 +\- sqrt( 25 + 704) )/ 2
= ( -5 +\- sqrt (729) ) /2 => as sqrt(729) = 27
= (-5 +\- 27) / 2 =>
= (-5 + 27)/2 or ( -5 -27)/2 =>
= 22/2 or -32/2 =>
= 11 or -16
But -16 is not allowed as the question wants a positive value.
Thank you,
MrB
I only see a black image, can you resend the image? or type it out here
