Question

ab -[ bc - ca-{ab-(3b-ac)-(ab-bc)}]

Answer 1

math](a+b+c)^2=a^2+b^2+c^2+2(ab+bc+ca)\\ 15^2=a^2+b^2+c^2+2\times71\\a^2+b^2+c^2 =83\tag*{}[/math] ...

Missing: 3b ‎| ‎Must include: ‎3b