2 (a²+b²) = (a+b)²
2a² + 2b² = a² + 2ab + b² ---------------------------- as (a + b)² = a² + 2ab + b²
2a² - a² + 2b² - b² – 2ab = 0
a² + b² – 2ab = 0 ------------------------- as (a – b)² = a² – 2ab + b²
(a – b)² = 0
a – b = 0
a = b
Hence proved
Written on Nov. 19, 2020, 10:06 p.m.