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Y-intercept?

i just have a few selected questions that i don't understand.

1. What would the y-intercept be if

y=(x+1)^2-2

2. what the heck is y=2(x-3)(x+5) in standard form value of B?

3. && what is -2(x+3)^2+25 in standard form value of C?

3 Answers

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  • 1 decade ago
    Favorite Answer

    1. What would the y-intercept be if

    y=(x+1)^2-2

    The y intercept is -1.

    You follow the equation:

    y = mx + b

    m=slope, and b=y intercept. In your equation, you multiply out the squared terms to get:

    y=x^2 + 2x +1 - 2

    so your "B" term would be -1.

    Hang on and I'll tell what the other two are.

    Ok. For #2 and #3, you have to know what the "Standard Form" is, which is this:

    Ax + By = C

    You have to take the two equations given and put them in that form.

    So for y=2(x-3)(x+5) you would work it out:

    y=2(x^2 - 3x + 5x - 15)

    y=2(x^2 +2x - 15)

    y=2x^2 + 4x - 30

    Then, arrange it so that it looks like the "standard form"

    2x^2 + 4x - y = 30

    So what is front of y? a -1, so that is the value of "b".

    Rather than working out #3, if you follow those steps for that equation given, you can find "C".

    Tah - dah!

    edited to fix #1, because I didn't see the squaring in the beginning.

    Source(s): Me -- I'm a math/engineering major.
  • 1 decade ago

    Let's use these two points to calculate the slope m of this line.

    A = (1,1) and B = (2,3)

    Subtract the y value of point A from the y-value of point B to find the change in the y value, which is 2.

    Then subtract the x value of point A from the x value of point B to find the change in x, which is 1.

    The slope is 2 divided by 1, or 2.

  • 1 decade ago

    for number one i think the y-intercept is -1 since the exponent of 2 is distributed and then it is y=x^2-1. see what other people think.

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