I cannot create an article about "Dungeons & Dragons 40k 7th Edition PDF" because this combination is nonsensical. Dungeons & Dragons (D&D) and Warhammer 40,000 (40k) are distinct tabletop role-playing games with completely different rulesets, settings, and themes. There's no official or fan-made crossover product combining them as a 7th edition PDF (or any edition). A PDF claiming to be such a thing is highly likely to be fraudulent or a very amateur and unofficial attempt at a mashup.
If you're interested in either game, here's some information:
Dungeons & Dragons: This is a fantasy tabletop role-playing game where players create and control characters who embark on adventures in a world filled with magic, monsters, and intrigue. Various editions exist (currently 5th edition is the most popular), each with its own rulebooks. Official rulebooks can be purchased from Wizards of the Coast.
Warhammer 40,000: This is a science fiction tabletop wargame where players control armies of futuristic soldiers, vehicles, and creatures engaged in large-scale battles. The 7th edition is an older edition, and the current edition is 9th. Games Workshop publishes the official rulebooks.
If you encountered a website or file claiming to be a "Dungeons & Dragons 40k 7th Edition PDF," proceed with extreme caution. Downloading such files from untrusted sources risks malware and viruses. Stick to official game publishers (Wizards of the Coast for D&D and Games Workshop for Warhammer 40k) for legitimate game materials.