1. Tim \(x\in Z\)de \(A\in Z\)A= \(\frac{x+5}{x+3}\)2. Tim GTLN hoac GTNN cua bieu thuc:A= -7+/2-x/B= 5- /2x+3/3. Tim \(x\in Z\)a) \(7⋮x+3\)b) \(x+4⋮x+1\)c) \(4x+3⋮x+2\)d) \(\left(x+1\right)+\left(x+2\right)+...+\left(x+9\right)+\left(x+10\right)=5\)e) \(\left(x-10\right)+\left(x-9\right)+...+\left(x-1\right)=-2015\)i) (-4)3 + /x/=2010k) /x+5/ \(\le2\)l) /x+3/ = x-14. Chung minh rang:\(A=1-3+3^2-3^2+...+3^{98}-3^{99}⋮4\) (giai ho mk nhe! thu 2 phai nop roi! ban nao giai duoc nho giai...
Đọc tiếp
1. Tim \(x\in Z\)de \(A\in Z\)
A= \(\frac{x+5}{x+3}\)
2. Tim GTLN hoac GTNN cua bieu thuc:
A= -7+/2-x/
B= 5- /2x+3/
3. Tim \(x\in Z\)
a) \(7⋮x+3\)
b) \(x+4⋮x+1\)
c) \(4x+3⋮x+2\)
d) \(\left(x+1\right)+\left(x+2\right)+...+\left(x+9\right)+\left(x+10\right)=5\)
e) \(\left(x-10\right)+\left(x-9\right)+...+\left(x-1\right)=-2015\)
i) (-4)3 + /x/=2010
k) /x+5/ \(\le2\)
l) /x+3/ = x-1
4. Chung minh rang:
\(A=1-3+3^2-3^2+...+3^{98}-3^{99}⋮4\)
(giai ho mk nhe! thu 2 phai nop roi! ban nao giai duoc nho giai nhanh gium mk nhe, mk mang on suot doi luon!)
1,
để A thuộc Z thì
x+5 chia het cho x+3
co x+3 chia het cho x+3
=>(x+5)-(x+3)chia het cho x+3
hay2 chia het cho x+3
=>x+3 thuộc ước của 2
=>x+3 thuoc {1,-1,2,-2}
ta co bang
vay de A thuoc Z thi x thuoc {-2,-4,-1,-2}