Question

1. Show that

(10a + 5)^2 = 100a(a + 1) + 25,
for every a real number. How is this formula explaining the rule we have, to square a number
which ends in 5, such as
25^2 = 625, 35^3 = 1225, 105^2 = 11025^2, etc. ?

Answer 1

(10a+5)²= 100 a( a+1) + 25

Explanation:

Explanation:-

Given

(10a+5)²

By using (a+b)² = a² +2ab +b²

= (10a)²+ 2 × 10a× 5 + (5)²

= 100a² + 100a + 25

= 100 a( a+1) + 25