Question

若ma的n次方乘b的3次方是关于a,b的五次单项式,且系数为-3,则mn等于多少?

Answer 1

关于a,b的五次单项式,且系数为-3,
所以m=-3
a和b的次数之和是5
所以n+3=5
n=2
所以mn=-3×2=-6

Answer 2

关于a,b的五次单项式,且系数为-3,
所以m=-3
a和b的次数之和是5
所以n+3=5
n=2
所以mn=-3×2=-6

Answer 3

(x-0.7)³=0.3³
x-0.7=0.3
x=1
令a=x+1
则x=a-1
所以f(a)=-(a-1)²+4=-a²+2a+3
所以f(x)--x²+2x+3

设提高2元的x倍
则加个是2x+10元
床位是100-10x
则(2x+10)(100-10x)
=-20x²+100x+1000
=-20(x-2.5)²+1125
x是整数
则x=2和3时最大
投资少则床位少
即100-10x小
所以x=3
2x=6
所以应提高6元

Answer 4

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