Question

因式分解(本題共2小題，每小題4分，共8分)
（1）a² (x ?y) + b² (y ?x)             （2）x⁴ ? 18x² + 81

Answer 1

(1) (x ?y) (a + b) (a ?b) (2) (x + 3)² (x? 3)²

(1) 解：原式= a²(x?y)?b²(x ?y) =(x ?y) ( a² ?b²) =(x ?y) (a + b) (a ?b)
(2) 解：原式= (x²? 9)² = [(x + 3) (x? 3)]² = (x + 3)² (x? 3)²