先化简,再求值1.18a²-{-6a²+[5a-4a²-(a²-2a²)]+15a²-5a},其中a=5分之12.已知M=2x²+3kx-2x+6,N=-x²+kx+2,且3M+6N的值与X无关,求k的值

先化简,再求值
1.18a²-{-6a²+[5a-4a²-(a²-2a²)]+15a²-5a},其中a=5分之1
2.已知M=2x²+3kx-2x+6,N=-x²+kx+2,且3M+6N的值与X无关,求k的值

1.18a²-{-6a²+[5a-4a²-(a²-2a²)]+15a²-5a}
=18a²-{-6a²+[5a-4a²-a²+15a²-5a}
=18a²-{-6a²+10a²}
=14a²
当a=1/5时,原式=14×1/25=14/25
2.3M+6N
=3（2x²+3kx-2x+6）+6（-x²+kx+2）
=6x²+9kx-6x+18-6x²+6kx+12
=(15k-6)x+30
∵3M+6N的值与X无关
∴15k-6=0
k=2/5

1. 18a²-{-6a²+[5a-4a²-(a²-2a²)]+15a²-5a}
=18a²+6a²-5a+4a²+a²-2a²-15a²+5a
=11a²
=11/25
2. 3M+6N=3(2x²+3kx...

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1. 18a²-{-6a²+[5a-4a²-(a²-2a²)]+15a²-5a}
=18a²+6a²-5a+4a²+a²-2a²-15a²+5a
=11a²
=11/25
2. 3M+6N=3(2x²+3kx-2x+6)+6(-x²+kx+2)
=6x²+9kx-6x+18-6x²+6kx+12
=(15k-6)x+30
因为3M+6N的值与X无关,所以
15k-6=0
则k=6/15=2/5

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