# simultaneous equations

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• May 25th 2008, 08:39 PM
Xelax
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. • May 26th 2008, 05:50 AM mr fantastic Quote: Originally Posted by Xelax 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 .....

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