化简代数式,求值 !~

2024-12-16 13:21:35
推荐回答(1个)
回答1:

解:1:①a²-b²/a=2²-1²/2=7/2
②a²-b²/a=(2/3)²-(1/9)²×3/2=11/27
2:3x²-x=1
6x³+7x²-5x+2006
=6x³-2x²+9x²-5x+2006
=2x(3x²-x)+3(3x²-x)-2x+2006
=2x+3-2x+2006
=2009
3:当x=-5时,y=3
∴(-5)^4a+(-5)²b+c=3
5^4a+5²b+c=3
当x=5时,
y=5^4a+5²b+c=3
4:①∵x+1/x=3
∴(x+1/x)²=3²
x²+2+1/x²=9
x²+1/x²=7
②x³+1/x³=(x+1/x)(x²-1+1/x²)
=3×(7-1)
=18