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## Homework Statement

let

*a,b,c*be three integers is

*a*divides

*c*and

*b*divides

*c*, then either

*a*divides

*b*or

*b*divides

*a*.

if

*a,b,c,d*are real numbers with

*a*<

*b*and

*c*<

*d*, then

*ac*<

*bd.*

## Homework Equations

## The Attempt at a Solution

So for part 1

Since a/c and b/c

then, c=ak and c=bd for some integers k,d.

hence, ak=bd

so a/b=d/k

where d/k =l for some integer l.

so a/b=l... Therefore a/b. end of proof.

for part 2)

a<b and c<d (given).

let a= -5 and b=-4 satisfying a<b

and let c=-7 and d=-5 satisfying c<d

so then ac

= 35

and bd

= 20

so 35<20

but this is false

therefore ac<bd is false. end of proof.

Can Someone please tell me if I have done this correctly?