CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

If $$7th$$ term of $$AP$$ is $$7$$ times is equal to $$11$$ times of $$11th $$term of $$AP$$ the that $$18th$$ term is zero.


Solution

Given $$7^{th}$$ term of A.P is equal to $$11$$ terms the $$11^{th}$$ term of A.P.
Let $$7^{th}$$ term of A.P$$=a+(n-1)d$$
$$=a+(7-1)d$$
$$=a+6d$$
d- common difference
a- first term
$$11^{th}$$ term of A.P$$=a+(11-1)d$$
$$=a+10d$$
Given, $$7(a+6d)=11(a+10d)$$
$$7a+42d=11a+110d$$
$$\Rightarrow 4a=-68d$$
$$\Rightarrow a=-17d$$ ………..$$(1)$$
$$18^{th}$$ term of A.P$$=a+(18-1)d$$
$$=a+17d$$ [From $$(1)$$]
$$=-17d+17d$$
$$=0$$.

1172776_1267858_ans_6b66b3f5e567441cb271eb71f69cd45f.jpeg

Mathematics

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image