find the 31st term of an AP Where 11th term is 38 and 16th term is 78
Answers
Answered by
2
A+10d=38
And
A+15d=78
Solving equations u get d= 8 and A= -42
Now A+30d=31st term
-42+30(8)= 198
And
A+15d=78
Solving equations u get d= 8 and A= -42
Now A+30d=31st term
-42+30(8)= 198
Answered by
1
a+10d=38
a+15d=78
.................
-5d=-35
...................
d=-35÷-5=7
put in a+10d=38
a+10(7)=38
a+70=38
a=38-70=-32
a=-32
put in identity a+(n-1)d
-32+(31-1)7
-32+30×7
-32+210
178 is 31st term
a+15d=78
.................
-5d=-35
...................
d=-35÷-5=7
put in a+10d=38
a+10(7)=38
a+70=38
a=38-70=-32
a=-32
put in identity a+(n-1)d
-32+(31-1)7
-32+30×7
-32+210
178 is 31st term
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