Write the quadratic equation whose roots are 5 and -4, and whose leading coefficient is 4 use the letter x to represent the variable

Ineed with number 17 i don’t get it at alll

Determine the mean and variance of the random variable with the following probability mass function. f(x)=( 729divided by 91) (1 divided by 9) superscript x baseline comma x equals 1,2,3 round your answers to three decimal places (e.g. 98.765).

Cot(90° − x) = 1 the value of x that satisfies this equation is °. a. 60 b. 135 c. 225 d. 315