一、外因内移法将根号外的正因式移入根号内,把比较二次根式的大小转化为比较被开方数的大小.例1比较7!6与6!7的大小.解:7!6=!72×6=!294,6!7=!62×7=!252,因为!294!252,所以7!66!7.二、平方法两边同时平方,把比较二次根式的大小转化为比较幂的大小.例2比较!13+!7与!17+!3的 First, the external factor inward shift method moves the positive factor outside the root number into the root number, and converts the size of the comparative secondary root pattern into the size of the compared open square. Example 1 compares the sizes of 7!6 and 6!7. Solution: 7!6=!72×6=!294,6!7=!62×7=!252, because !294!252, so 7!66!7. Two, flat method on both sides at the same time square, compare the secondary roots The size is converted to a relatively power-size. Example 2 Comparison !13+!7 and !17+!3