Question 1172467
<pre><font face = "consolas" color = "indigo" size = 4><b>
Hi  
The 7th term of an AP is 17 and the 13th term is "12 more than the 7th term". 
find the first term:
 {{{a[n]=a[1]+(n-1)*d}}}
{{{a[13]=29 = a[1] + 12d}}}
{{{ a[7]= 17 =  a[1] + 6d}}}   |Subtracting 2nd EQ from 1st EQ  eliminating {{{a[1]}}}
12 = 6d
{{{red(d=2)}}}
{{{17 = a[1] + 6d}}} |Finding a(1)
{{{17 = a[1] + 12}}}
{{{green(a[1] = 5)}}}

CHECKING our answer***
{{{29 = a[1] + 12d}}}
29 = 5 + 24 CHECKS!!
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