Question

If the 11 th term of arithmatic progression is 44 and 16 th term is 19 find the 20 th term and the arithmatic progression

Answer 1

a+19d=? equation 3 , a+10d=44 this is first equation , a+15d=19 this is second equation, we can solve it by subtracting both the equation, we find d= -5this value of d in put the second equation then a is 94, then the value of a and d in put the equation 3, 94 + 19 into -5= a20, the 20th term is -1, we can use the formula a+(n-1)d. The ap is -1,-6,-11 .....

Answer 2

a11=a+ 10d=44........(1)
a16=a+15d=19.........(2)
(-) (-) (-)
__________
-5d=25
d=-5
putting the value of d in eq (1)
a+10d=44
a+10*(-5)=44
a-50=44
a=44+50
=94
a20=a+19d
=94+19*(-5)
=94-95
=-1


hope this will helpyou