用等值演算法证明下面等值式：<img src='https://fb.fenbike.cn/api/planet/accessories/formulas?fontSize=18&latex=krIXAojp7ugJIO7ZL1Z1ErD_1nt2vE3THXKvUOw2Qwqa2b7wQV5YKTtd0VC4E4tfXUFiT_dv8x0dmENPSOv4_w' />。