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Math Help - help with circle and points on a line

  1. #1
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    help with circle and points on a line

    1) Find the values of a and b if (3a + 11, 2b - 5) = (3,-2).
    Do I have have to substitue 3 into a, and -2 into b???

    2) Find an equation for the given points on a line (-2,-3) and (5,-4).
    Is it y= -1/7(x) - 23/7?

    3) Find an equation of a circle with center (-2,-3) tangent to the line y=7.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by NeedHelp18 View Post
    1) Find the values of a and b if (3a + 11, 2b - 5) = (3,-2).
    Do I have have to substitue 3 into a, and -2 into b???
    no.

    notice the colors: ({\color{red}3a + 11}, {\color{blue}2b - 5}) = ({\color{red}3}, {\color{blue}-2})

    now do you see what to do?

    2) Find an equation for the given points on a line (-2,-3) and (5,-4).
    Is it y= -1/7(x) - 23/7?
    yes

    3) Find an equation of a circle with center (-2,-3) tangent to the line y=7
    the equation of a circle with center (h,k) and radius r is given by:

    (x - h)^2 + (y - k)^2 = r^2

    we want this circle to touch the line y = 7 at one point. think of how large the radius must be to touch the line y = 7
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  3. #3
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    ok i hope this is right...

    is it

    (x + 2)^2 + (y + 3)^2 = 100
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by NeedHelp18 View Post
    ok i hope this is right...

    is it

    (x + 2)^2 + (y + 3)^2 = 100
    yes
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