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Can someone pls ! pls answer all. no explanation needed..

Aquadratic equation in standard from is written ax^2= bx+c, where a,b and c are real numbers and a is not zero?

F. a fair coin is thrown in the air four times. if the coin lands with the head up on the first three tosses, what is the probability that the coin will land with the head up on the fourth toss? a. 0 b. 1/16 c. 1/8 d. 1/2