高数题,求x趋近于无穷时,1+x分之x+3的x+5次方的极限?
3个回答
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(x+3)/(x+2)
=1 + 2/(x+2)
令
1/y = 2/(x+2)
x+2 =2y
x=2y-2
lim(x->无穷) [(x+3)/(x+2)]^(x+5)
把(x+3)/(x+2) 变成 =1 + 2/(x+2)
=lim(x->无穷) [1 + 2/(x+2)]^(x+5)
令 1/y = 2/(x+2)
=lim(x->无穷) [1 + 1/y]^(2y-2+5)
=lim(x->无穷) [1 + 1/y]^(2y+3)
=lim(x->无穷) [1 + 1/y]^(2y)
=e^2
得出结果
lim(x->无穷) [(x+3)/(x+2)]^(x+5) =e^2
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