0 like 0 dislike
18 views
Calculate $n$ if $\sum_{k=1}^{n} (4 - 3k) = -125$
in Grade 12 Maths by | 18 views

1 Answer

0 like 0 dislike
T1= 4-3(1)=1

T2=4-3(2)= -2

T3=4-3(3)= -5

T4= 4-3(4)= -8

There is common difference , -2-1= -5-(-2)= -3

sum of arithmetic = n(2a+(n-1)d)/2

                  -125= 20(2(1)+(n-1)(-3))/2

                 -12.5 = 2-3n+3

                3n= 12.5+2+3

                  3n= 17.5

                      n= 8.83
by Diamond (85.5k points)

Related questions

0 like 0 dislike
1 answer
asked Mar 5, 2019 in Grade 12 Maths by TEDSF Platinum (114k points) | 20 views
Welcome to MathsGee Open Question and Answer Bank, a platform, where you can ask Maths and Science questions and receive answers from other members of the community. Help is always 100% FREE!
MathsGee QnA is the knowledge-sharing community where millions of students and experts put their heads together to crack their toughest homework questions.

Enter your email address: