College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 5, Systems of Equations and Inequalities - Section 5.4 - Systems of Nonlinear Equations - 5.4 Exercises - Page 466: 42

Answer

$(1,3)$ and $(3,1)$

Work Step by Step

Let $m=2^x$ and $n=2^y$. Then, we have $m+n=10$ $m^2+n^2=68$ Rewrite this system: $n=10-m$ $m^2+n^2-68=0$ Substitute the first equation to the second one and then solve for $m$: $m^2+(10-m)^2-68=0$ $m^2+m^2-20m+100-68=0$ $2m^2-20m+32=0$ $(2m-4)(m-8)=0$ $m=2$ and $m=8$ Now, obtaine $n$: For $m=2$, $n=10-2=8$ For $m=8$, $n=10-8=2$. Obtaine $x$ and $y$: For $(m,n)=(2,8)=(2^1,2^3)$, we get $(x,y)=(1,3)$ For $(m,n)=(8,2)=(2^3,2^1)$, we get $(x,y)=(3,1)$ Therefore, the solutions are $(1,3)$ and $(3,1)$.
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