You may want to ask on the SFML forums, as it looks like SFML is linking to SOIL already (which is why you're getting all these double definition errors), but apparently you can't access all of SOIL's functions (which would be why you got the first two errors).
thanks for the reply.
is there a reason why i cannot access all of soil's function?
now after i deleted the sfml from the project property, i got the following errors:
1>------ Build started: Project: Fractals with zoom, Configuration: Release Win32 ------
1>libSoil.a(stb_image_aug.o) : error LNK2001: unresolved external symbol __alloca
1>libSoil.a(image_helper.o) : error LNK2001: unresolved external symbol _sqrtf
1>C:\Users\rob\DevC++ source\MSVC++\freeglut\fractal\Dynamical system and fractals\Fractals with Zoom\Release\Fractals with zoom.exe : fatal error LNK1120: 2 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========