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Math Help - Literal equation for the indicated variable

  1. #1
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    Literal equation for the indicated variable

    1. 2x + 3y = 6 (for x) Linear equation





    2. D = C - s/n (for s) Depreciation






    3. A = 1/2 h(B = b)(for b) Area of Trapezoid
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Patience View Post
    1. 2x + 3y = 6 (for x) Linear equation





    2. D = C - s/n (for s) Depreciation






    3. A = 1/2 h(B = b)(for b) Area of Trapezoid
    ok, i suppose you want us to solve for the indicated variable.

    1. 2x + 3y = 6
    => 2x = 6 - 3y .......................subtracted 3y from both sides
    => x = (6 - 3y)/2 ....................divided by 2 on both sides
    => x = 3 - (3/2)y ....................simplified

    2. D = C - s/n
    => D - C = -s/n ......................subtracted C from both sides
    => -n(D - C) = s .....................multiplied both sides by -n
    => s = -n(D - C)

    3. A = 1/2 h(B - b)
    => 2A = h(B - b) ...................multiplied both sides by 2
    => 2A/h = B - b ....................divided both sides by h
    => 2A/h - B = -b ...................subtracted B from both sides
    => B - 2A/h = b ....................multiplied both sides by -1
    => b = B - 2A/h ....................rewrite
    Last edited by Jhevon; March 1st 2007 at 10:43 PM.
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  3. #3
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Patience View Post
    3. A = 1/2 h(B = b)(for b) Area of Trapezoid
    Quote Originally Posted by Jhevon View Post

    3. A = 1/2 h(B - b)
    => 2A = h(B - b) ...................multiplied both sides by 2
    => 2A/h = B - b ....................divided both sides by h
    => 2A/h - B = -b ...................subtracted B from both sides
    => B - 2A/h = b ....................multiplied both sides by -1
    => b = B - 2A/h ....................rewrite
    This is a good analysis, but the original equation is incorrect:
    A = (1/2)h(B + b)

    You can do Jhevon's solution with the change in sign for practice. The method is identical. I get:
    b = 2A/h + B

    -Dan
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by topsquark View Post
    This is a good analysis, but the original equation is incorrect:
    A = (1/2)h(B + b)

    You can do Jhevon's solution with the change in sign for practice. The method is identical. I get:
    b = 2A/h + B

    -Dan
    Ah, yes, its the equation for the area of a trapezium, my bad
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