Doesn't matter. It's an Intel socket motherboard from what I can tell, so no AMD CPU will fit. Even assuming one did fit, it wouldn't work. If it is actually an AMD socket board, you'd still be limited to CPUs from the same general family and that would probably put it around the Athlon X2 maybe original Phenom days at best.
To use a more recent AMD CPU, you'd have to replace the motherboard which would likely require new RAM and would certainly require a new copy of Windows (or another OS like Linux). Replacing the motherboard on a slimline model will be no easy task, particularly because it will be difficult sourcing one that would fit inside the case. You could replace the case, but then you'd need a new PSU because the slimline one wouldn't fit in a standard ATX case. So at the end of the day, you've built an entirely new computer rather than just upgraded the old one. You can salvage the HDD and optical drive for sure, probably a coin toss on the RAM at best.
As Digger said, you buy a brand name computer, like Dell, you should expect that your upgrade options will be limited. That goes at least double for slimline and all-in-one desktops as well as laptops. Also as a general rule of thumb, the cheaper the unit retails for, the less upgrade potential it has. Inspiron has always been Dell's budget consumer brand, so you get an Insprion slimline desktop, you should expect virtually nothing in the way of upgrade potential. Don't even bother because you'd just be throwing your money away. Stick it in a bank account, stuff it into a mattress, collect it in a jar, whatever works for you, but put anything you were thinking of spending on an upgrade for that system towards a brand new one. It will be far better spent in that manner than trying to do any kind of upgrade to an older slimline model.