Method of substitution replaces some quantities in the function formula with new variables, so that the function is transformed into a function form with new variables as independent variables, and then the range of values is obtained. Example 2 Find the range of the function y=x-3+√2x+ 1 Hugging: the original function is transformed into a quadratic function of variables through substitution, and the value range of the original function is determined by the maximum value of the quadratic function. Solution: Let t=√2x+ 1(t≥0), then x= 1/2(t2- 1). So y =1/2 (T2-1)-3+t =1/2 (t+1) 2-4 ≥1/2-4 =-7/2. Therefore, the range of the original function. Comments: Convert irrational function or quadratic function into quadratic function, and determine the range of the original function by finding the maximum value of quadratic function. This method of solving problems embodies the thinking method of method of substitution and induction. It is widely used. Exercise: Find the range of function y = √ x-1–X. (Answer: {y | y ≤-3/4} See the website: /shuxue/ Jiang Jie/19694.html, which contains nine methods and examples to explain the definition of function evaluation in senior high school. I wish you success in your studies. . .