Question

Hey !

Question ;-

Explain why 7*11*13+13 and 7*6*5*4*3*2*1+5 are composite numbers.

Class X (Maths)

Answer 1

in first case take 13 common out side

(7×11+1)13= (78)13 and product is composite no.

similarly take 5 common

(7×6×4×3×2×1+1)5

=(1009)5

which is also composite no. as simple property a no. having the two factor other than no. itself and 1 is composite no.

Answer 2

$\huge \boxed{hello \: mate}$

1)

=>7×11×13+13

=>13(7×11+1)

=>13(77+1)

=>13×78

=>13×2×3×13

2)

=>7×6×5×4×3×2×1+5

=>5(7×6×4×3×2×1+1)

=>5(1008+1)

=>5(1009)

= >5×1009

Since, the numbers formed have more than 2 factors(other than 1 and the number itself) and can be written in prime factors, hence they are composite numbers.