# A term in an arithmetic sequence and the common difference. Given #a_15=272# and d=20, how do you find the first three terms?

##### 1 Answer

Dec 21, 2016

#### Explanation:

For the standard arithmetic sequence, the nth term is.

#color(red)(bar(ul(|color(white)(2/2)color(black)(a_n=a_1+(n-1)d)color(white)(2/2)|)))#

where#a_1" is first term"# here

#a_15=272" and " d=20# and we want to find

# a_1,a_2" and " a_3#

#rArr272=a_1+(14xx20)#

#rArra_1=272-280=-8#

#rArra_2=-8+d=-8+20=12#

#rArra_3=12+20=32#