Every answer i tried was wrong. i tried a=pi•r^2/2 and got approx. 19.81, and its incorrect. what am i doing wrong?

What is the y intercept of f(x)=(1/2)^x?

Which of the following describes the graph of y--4x-36 compared to the parent square root function? stretched by a factor of 2, reflected over the x-axis, and translated 9 units right stretched by a factor of 2, reflected over the x-axis, and translated 9 units left stretched by a factor of 2, reflected over the y-axis, and translated 9 units right stretched by a factor of 2, reflected over the y-axis, and translated 9 units left save and exit next submit

Evaluate the discriminant of each equation. tell how many solutions each equation has and whether the solutions are real or imaginary. x^2 - 4x - 5 = 0