Algebra: A Combined Approach (4th Edition)

Published by Pearson
ISBN 10: 0321726391
ISBN 13: 978-0-32172-639-1

Chapter 11 - Section 11.3 - Solving Equations by Using Quadratic Methods - Exercise Set - Page 787: 17

Answer

$x=-.5, .5, -i\sqrt 3, i\sqrt 3$

Work Step by Step

$4x^4+11x^2=3$ $y=x^2$ $4x^4+11x^2=3$ $4(x^2)^2+11x^2-3=3-3$ $4y^2+11y-3=0$ $y=(-b±\sqrt {b^2-4ac})/2a$ $y=(-11±\sqrt {11^2-4*4*-3})/2*4$ $y=(-11±\sqrt {121+48})/8$ $y=(-11±\sqrt {169})/8$ $y=(-11±13)/8$ $y=(-11+13)/8$ $y=2/8$ $y=1/4$ $y=(-11-13)/8$ $y=-24/8$ $y=-3$ $y=x^2$ $1/4=x^2$ $\sqrt {1/4} =\sqrt {x^2}$ $x=±1/2$ $x^2=-3$ $\sqrt {x^2} = \sqrt {-3}$ $x=\sqrt {-3}$ $x=\sqrt {3*-1}$ $x=±i\sqrt3$
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