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Math Help - simultaneous equations

  1. #1
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    simultaneous equations

    Can someone please help me with these two.


    1." A total of 12,000 is invested in two funds paying 9% and 11% simple interest. If the yearly interest is $1,180, how much of the 12,000 is invested at each rate? USE A MATRIX METHOD TO SOLVE THIS QUESTION."


    2." x^2 + y^2=57
    x+2y=1"


    Note: ^= Sqaured by.
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  2. #2
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    Quote Originally Posted by Xelax View Post
    Can someone please help me with these two.


    1." A total of 12,000 is invested in two funds paying 9% and 11% simple interest. If the yearly interest is $1,180, how much of the 12,000 is invested at each rate? USE A MATRIX METHOD TO SOLVE THIS QUESTION."

    Mr F says: The two equations you need to solve simltaneously are:

    x + y = 12,000 .... (1)

    {\color{red}\frac{9x}{100} + \frac{11 y}{100} = 1180 \Rightarrow 9x + 11y = 118,000} .... (2)

    I'll assume I've done the heavy lifting and that you can express equations (1) and (2) as a matrix equation, and that you can solve this matrix equation (reviewing your class notes and/or textbook might help here).


    2. x^2 + y^2=57 .... (1)
    x+2y=1 => x = 1 - 2y .... (2)

    Mr F says: Start by substituting (2) into (1) and solving the resulting quadratic equation for y .....

    [snip]
    ..
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