Question

(4) If (a + b + c) (a - b + c)= + b3 + c show that a, b, c are in continued proportion.​

Answer 1

Answer:

(a+b+c) (a-b+c)

=a(a-b+c) + b(a-b+c) +c(a-b+c)

=a²-ab+ca+ab-b²+bc+ca-bc+c²

=a²-b²+c²