Question

explain why 7×11×13+13 and 7×6×5×4×3×2×1+5 are composite numbers​

Answer 1

Answer:

Step-by-step explanation:

Answer 2

7×11×13+13 may be written as, 13x{(7x11) + 1} i.e. 13x(78). So other than 1 and the number itself, 13 and 78 are also the factors of the number. Further, 78=39x2. So, 39 and 2 are also it's factors. So this number is definitely not prime. Hence its composite number.

Similarly, 7×6×5×4×3×2×1+5 can be written as 5x{(7x6x4x3x2x1)+1}, i.e. 5x(1009). So, other than the number and 1, it have 5 and 1009 as it's factors too. So it is also a composite number.