【範例29】
29-1.若a+b=3,ab=1,試求:
(1) a²+b²=【
】(2) a³+b³ 【
】(3
29-2.設實數x,y滿足x+2y=3,x²+8=9,求x² + 42 =
x+2y³-6xy (x + 2y
=> x y = 1
=+b² = (a+b)²= Lab
3²-2
= 7
+b² = (a+b) ³ ³ ab(a+b)
33-3(3)
= 27-9
= 18
OPPO Reno5 Z
答案: (1
3) a-1)= (a+b)-4
2
= (a+b)² = 3²=
=(a+b)²= 5
=
a-b=±5
(4)
