Can i girl get pregnant if the man entered penis inside vagina immediately after masturbation and ejaculate into vagina?

Yes: Any of the fluids from an excited males penis that come in contact with the inside of a woman's genitals can cause pregnancy. It only takes one healthy sperm to do the trick & many more are usually present.

Yes: That is exactly how you get pregnant. I recommend that you talk to a sex educator or your doctor for further information including information about contraception.