Question

find the messing term of the AP-13,-3.
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Answer 1

Answer

l=a−3d

13=a−d

m=a+d

3=a+3d

a−d=13 -(i) a+3d=3 -(ii)(i)−(ii)

a−d−a−3d=13−3−4d=10d= 2−5=−2.5a=13+d=13−2.5=10.5l=a−3d=10.5+3(2.5)=10+.5=18m=a+d=10.5−2.5=8