Limits of Integration in Substitution Method

① This example demonstrates how to adjust the limits of integration when applying the substitution method to definite integrals, ensuring that the new integral interval matches the substituted variable. ② The core mathematical concept is u-substitution in definite integrals, emphasizing that when changing variables from x to u, the original integration limits must be transformed accordingly to avoid incorrect results. ③ Construction details: Based on the construction summary, the example uses GeoGebra's Integral command with functions f, g and parameters a, b, visually showing the relationship between the original and substituted integration regions to clarify the geometric meaning of the limits. ④ Suitable for senior high school or early college calculus students to reinforce this critical step, and useful for teachers as a classroom demonstration tool.