Can you help solve these equations?

Question

can you help me find the intercepts?

1.) y = -x^2 + 9

2.) y= x^2 -9

Answer 1

If you want to find the y-intercept, then you must make "x" equal to 0. If you want to find the x-intercept, then you must make "y" equal to zero

1)
y = -x^2 + 9
y = -(0)^2 + 9
y = 9

Y-int = 9

y = -x^2 + 9
0 = -x^2 + 9
-9 = -x^2
9 = x^2
+/- 3 = x

X-int = +/- 3


2.)
y= x^2 -9
y= 0^2 - 9
y = -9

Y-int = -9

y= x^2 -9
0 = x^2 - 9
9 = x^2
+/- 3 = x

X-int = +/- 3

Answer 2

1)

y = -x^2 + 9

to get x-intercept put y = 0

0 = -x^2 + 9

x^2 = 9

x = +/- 3

to get y intercept put x = 0

y = 9

so x intercepts = 3 or -3 and y intercept = 9

2)

y = x^2 - 9

0 = x^2 - 9

x^2 = 9

x = +/- 3

y = 0 -9

y = -9

x- intercepts = 3 or -3

y - intercept = -9

Answer 3

you add the two equations together:

y + y = -x^2 + 9 + x^2 - 9
2y = 0
y = 0

then you plug this into either equation:

0 = -x^2 + 9
x^2 = 9

then take the square root of both sides:

x= 3 or -3

so they intersect at (0,-3) and at (0,3)

Answer 4

both x intercepts are (-3,0) and (3,0)

y intercept is (0,9) and (0,-9)