Question

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!)

 

Answer 1

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

x+3	1	-1	2	-2
x	-2	-4	-1	-5

vay de A thuoc Z thi x thuoc {-2,-4,-1,-2}