‏设<img src="https://static.zxtiku.com/wangke/imgs/topic/2d05d18a288ad597fc4aec4f9ff7a8d9.png"/>在<img src="https://static.zxtiku.com/wangke/imgs/topic/142b254fa5673e0b28fb75975a365e9b.png"/>上为增函数，并且<img src="https://static.zxtiku.com/wangke/imgs/topic/af10fad6cb3d047f0f89d732b39cef4c.png"/>，<img src="https://static.zxtiku.com/wangke/imgs/topic/94ff71d5d7e9cbb8eaaf21f0ab0904e2.png"/>，则必有<img src="https://static.zxtiku.com/wangke/imgs/topic/935f6e7549c220be4696b1476391b9a0.png"/>使<img src="https://static.zxtiku.com/wangke/imgs/topic/8487eb80119c7570f21093e95abf5bf4.png"/>.‎