49 (a + b) & # 178; - 16 (a-b) & # 178; calculated by formula or extracting common factor

49 (a + b) & # 178; - 16 (a-b) & # 178; calculated by formula or extracting common factor

49(a+b)²-16(a-b)²
=(7a+7b+4a-4b)(7a+7b-4a+4b)
=(11a+3b)(3a+11b)