Question

Find the sum of the first fifteen multiples of 5.?

Answer 1

Answer:

Step-by-step explanation:

first multiple of 5 is 5

15 th multiple is 75

now lets use arithmetic progression

common difference d is 5

first term a=5

formula:

sum=n/2[first term + last term]

n=15

sum=15/2[75+5]

=15 x 40

=600

check it

5+10+15+20+25+30+35+40+45+50+55+60+65+70+75=600

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Answer 2

Step-by-step explanation:

5,10,15,20,25,30,35,40,45,50,55,60,65,70,75