it is called linear because β0, β1, . . ., βp all have their exponents to be 1. A multiple linear regression is a type of regression which has more than one independent variable. it tells us the existing relationship between 2 or more of these independent variables on the dependent variable. for it to be regarded to be linear, it is very important that the exponents be equal to 1. else it could be quadratic.
The possibility of flipping heads is 1 in 2 (1/2) the possibility of pulling a black card is 26 in 52 (26/52) which equals 1 in 2 (1/2) multiply those together and you get 1 in 4, 1/4, or a 25%
