Let a and b with a > b > 0 be real numbers satisfying a3+b3=a+b.
Find (a+b)2−1ab.
Formula:a3+b3=(a+b)(a2−ab+b2)
a3+b3=(a+b)(a2−ab+b2)|a3+b3=a+b(a+b)=(a+b)(a2−ab+b2)a2−ab+b2=a+ba+ba2−ab+b2=1a2+b2−ab=1|a2+b2=(a+b)2−2ab(a+b)2−2ab−ab=1(a+b)2−3ab=1(a+b)2−1=3ab|:ab(a+b)2−1ab=3
