Question

Consider the Quadratic function f(x)=9x^2−9 The y value of the y-intercept is y= ?

Answer 1

(0,9)

Explanation:

What is the y-intercept?

The y-intercept of a function is the point where the function crosses the y-axis. It's usually written in the form (0,b) where b = the y-intercept.

How to find it?

To find a function's y-intercept, input 0 for x and solve for y:

• 
  `\bf{f(x)=9x^2-9}`
• 
  `\bf{f(0)=9(0)^2-9}`
• 
  `\bf{f(9)=9*0-9}`
• 
  `\bf{f(9)=-9}`

`\therefore` the y-intercept is (0,-9)

Answer 2

• Answer:

`\Large{\boxed{\sf y = -9 \Longleftrightarrow y-intercept = (0 \ , \ -9)}}`

`\\`

• Explanation:

Given function:

`\sf f(x) = 9x^2 - 9 \Longleftrightarrow y = 9x^2 - 9`

`\\`

The y-intercept of a function is the value at which the curve of said line crosses the y-axis. This happens when x = 0.

To find it, just substitute 0 for x:

`\sf \rightarrow y = 9(0)^2 - 9 \\ \\ \rightarrow \sf y = 9(0) - 9 \\ \\ \rightarrow \sf y = 0 - 9 \\ \\ \\ \rightarrow \boxed{\boxed{\sf y = -9 }}`