Question

What are the x– and y–intercepts of the quadratic equation y = (x – 1)2 – 16? Identify the x–intercepts by graphing the quadratic equation

Answer 1

the y intercept is value of y when x = 0

Answer 2

the x intercepts are values when y = 0

Answer 3

these are my choices:




x–intercepts: (3, 0) and (–5, 0)
y–intercept: (0, –16)
x–intercepts: (–3, 0) and (5, 0)
y–intercept: (0, –16)
x–intercepts: (3, 0) and (–5, 0)
y–intercept: (0, –15)
x–intercepts: (–3, 0) and (5, 0)
y–intercept: (0, –15)

Answer 4

replace x by 0 in the equation enables you to work out y intercept

y = (0-1)^2 - 16

Answer 5

can you work that out?

Answer 6

no im still confused

Answer 7

y = 1 - 16 (since (0-1)^2 = (-1)^2 = 1)

Answer 8

1 - 16 = ?

Answer 9

-15

Answer 10

right - so we now know that the y intercept iS (0,-15)
either 3rd or 4th option is correct

Answer 11

to find x intercepts

we solve the equation
(x - 1)^2 - 16 = 0 ( because y = 0 at the x-intercepts)

(x - 1)^2 = 16 (adding 16 to both sides of equation)
now take square root of both sides

x - 1 = 4 also x - 1 = -4 (both 4 and -4 squared = 16)

can you continue?

Answer 12

How would I continue?

Answer 13

first
x - 1 = 4 so what is x?

Answer 14

3?

Answer 15

no its 5

add 1 to both sides (to get x only on left side)

x - 1 + 1 = 4 + 1
x = 5

Answer 16

now we need to solve the second equation

x - 1 = -4

Answer 17

-3

Answer 18

right

so x intercepts = (5,0) and (-3,0) ( note that y = 0 at x-intercepts)

Answer 19

ahh I see how you did it

Answer 20

right - so you now correct option now

Answer 21

thx

Answer 22

yw

Answer 23

graph is below:
http://www.wolframalpha.com/input/?i=y++%3D+%28x+-+1%29%5E2+-+16+

Answer 24

thx!