The formula is a^2 - b^2 i got the answer for the b^2 but not a^2 i am getting 81x^4, where did i go wrong

The line y = x + passes through (−3, 7) and is parallel to y = 4x − 1.

True or false: the graph of y=f(bx) is a horizontal compression of the graph y=f(x) if b< 1

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)