高分！！这几道数学题怎么做
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2023年05月29日 04:40
热门回答（2个）
游客1
1.
A={x| x<<3 } , B={x|x
B is subset of A
=> a≤3
A是B的真子集
=> a<让瞎3
2.
a> b
=> a^2> b^2 (错）
e.g.
a= 1, b =-3
1>-3
但 1 <返锋 9
3.
x^2+bx+b>0
△ = b^2-4b >0
=> b(b-4)>0
b< 0 or b>4 #
4. 题目不清漏滑晌楚
5.
f(0) =1, ( I suppose)
f(x+1)-f(x)=2x
put x=0
f(1)-f(0)= 0
f(1) = 1
put x=2
f(2)-f(1) = 2
f(2) = 3
let f(x) = ax^2+bx+c
f(0) = c =1
f(x) = ax^2+bx +1
f(1) = a + b +1 = 1
b = -a
f(2) = 4a+2b+1 = 3
2a = 2
a = 1
b=-1
f(x) = x^2-x+1
游客2
a<3
a<=3
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