Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 10 - Section 10.8 - Systems of Nonlinear Equations - 10.8 Exercises - Page 755: 42

Answer

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

Work Step by Step

Given the system of equations: 1. $2^x + 2^y = 10$ 2. $4^x + 4^y = 68$ Reformat equation 2 1. $2^x + 2^y = 10$ 2. $(2^x)^2 + (2^y)^2 = 68$ The question asks to find all real solutions. Substitute $2^x = 10 - 2^y$ $(10-2^y)^2 + (2^y)^2 = 68$ $100 - 20 * 2^y + (2^y)^2 + (2^y)^2 = 68$ $2(2^y)^2 - 20 * 2^y + 32 = 0$ $2((2^y)^2 - 10 * 2^7 + 16) = 0$ $2((2^y - 2)(2^y - 8) = 0 $ $2^y = 2$ $y = 1$ $2^y = 8$ $y = 3$ Substitute the values into the equation $2^x = 10 - 2^1$ $2^x = 8$ $x = 3$ $2^x = 10 - 2^3$ $2^x = 2$ $x = 1$ All Solutions: $(3,1)$ $(1,3)$
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