Can Somebody help me real fast?

What is f(3) for the quadratic function f(x)= 2x^2+ + x - 12

What is the y-intercept of the line given by the equation

Circle a has a diameter of 7 inches, a circumference of 21.98 inches, and an area of 38.465 square inches. the diameter of circle b is 6 inches, the circumference is 18.84 inches, and the area is 28.26 square inches. part a: using the formula for circumference, solve for the value of pi for each circle. (4 points) part b: use the formula for area and solve for the value of pi for each circle. (4 points)