Question

Question no. 33 plzzzzz sole correctlyyy

Answer 1

Answer:

a16= 5( a3)

a+15d=5(a+2d)

a+15d=5a+10d

a-5a=10d-15d

-4a=-5d

a=5d/4............................(1)

Answer 2

Answer:

495

Step-by-step explanation:

we can write 3rd term as:-(a+2d).

And 16 th term as :-(a+15d).

According to question.

(a+2d)×5=(a+15d). [16th term is 5times to its 3rd term,so to form an equality].

Or,5a+10d=a+15d

Or,5a-a=15d-10d

Or,4a=5d

Or,a/d=5/4.

So,we can say that:-a=5. and d=4

Now we will put these values for get 3rd term in that equation.

which is (a+2d)=(5+2×4)

=5+8

=13

similarly for 16th term.

which is(a+15d).

Or,(5+15×4)

=65.

Now we can find the sum of 15 terms from starting.By using formula

Sn=n/2{2a+(n-1)d}.

=15/2{2×5+(15-1)4}. [on putting the above values].

=15/2{10+(14×4)}.

=15/2×66

=15×33

=495