Question

Jika a = b tunjukkan bahwa (a-b).(a+b)=0

Answer 1

(a-b)(a+b) =

= a^2 - ab + ab - b^2

= a^2 - b ^2

= b^2 - b^2 (dinasukan a = b)

= 0

sebenernya bisa juga

(a-b)(a+b) = 0

masukin a = b

(b-b)(a+b) = 0

0(a+b) = 0

0 = 0