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February 8th, 2015, 02:43 PM  #1 
Newbie Joined: Feb 2015 From: Brazil Posts: 3 Thanks: 0  System of Equations
Hello, my name is Gabriel and I'm from Brazil. This was one of the questions of my entrance test this year, which I take so I can attend a university, just like the SAT in the US. My math teacher couldn't solve it, neither could I. I used the TInspire CX CAS calculator to find the asnwer. May you try to solve it, please? Thank you! http://postimg.org/image/7vt9cd4dd/ 
February 8th, 2015, 03:10 PM  #2 
Math Team Joined: Jul 2011 From: Texas Posts: 2,885 Thanks: 1504  add 1st & 3rd equations ... $\displaystyle 2x1 + \leftx  \frac{1}{2} \right + 2^{y+1} = 11$ multiply by 2 ... $\displaystyle 22x1 + 2x  1 + 2^{y+2} = 22$ $\displaystyle 32x1+ 2^{y+2} = 22$ subtract the 2nd equation ... $\displaystyle 2^{y+1} = 8$ $\displaystyle y = 2$ substitute $\displaystyle y = 2$ into the 2nd equation ... $\displaystyle 32x1 + 8 = 14$ $\displaystyle x = \frac{3}{2} ; x = \frac{1}{2}$ you should be able to determine z from this point ... 
February 8th, 2015, 03:26 PM  #3 
Newbie Joined: Feb 2015 From: Brazil Posts: 3 Thanks: 0 
It looks so simple now! Haha. Thank you very much 

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