Question

explain step by step​

Answer 1

Hey! I hope you know the identity of

$( {a + b)}^{2} = \: {a}^{2} + \: {b}^{2} + \: 2ab$Now if you observe carefully..

10.5*10.5 + 15*10.5 + 7.5*7.5

(for Multiplication symbol used *)

${10.5}^{2} + 2 \times 7.5 \times 10.5 + {7.5}^{2}$

( as 15= 7.5*2)

So

$( {10.5 + 7.5)}^{2}$

= (10.5+ 7.5)(10.5+ 7.5)/10.5+ 7.5

Denominator got cancelled out by one of the numerator as they both are same.

= 10.5+ 7.5

= 18.0 ANSWER