Question

-1/5 - 4/7 -5/21 this is question​

Answer 1

Answer:

This alternating addition series begins with 3;

then 1 is added to give 4;

then 3 is added to give 7;

then 1 is added, and so on.

Rule = (first number + 1) (second number + 3) (third number + 1) (fourth number + 3)...

Now The series is 3, 4, 7, 8, 11, 12...

(3 + 1 = 4), (4 + 3 = 7), (7 + 1 = 8), (8 + 3 = 11), (11 + 1 = 12) (12 + 3 = 15)...

So the answer is d = 15.

Answer 2

$\huge \frac{-1}{⠀5} - \frac{4}{7} - \frac{5}{21}$

LCM of 5, 7, 21 is 105.

$\frac{1}{5}$ × $\frac{21}{21}$ = $\frac{21}{105}$

$\frac{4}{7}$ × $\frac{60}{105}$ = $\frac{60}{105}$

$\frac{5}{21}$ × $\frac{5}{5}$ = $\frac{25}{105}$

$\frac{-21-60-25}{105}$

$\frac{-81-25}{105}$ = $\frac{-106}{105}$

Answer :-

In Exact Form :- $\frac{-106}{105}$

In Decimal Form :- 1.00952380

In Mixed Fraction :- -1$\frac{1}{105}$