Question 822548: A computer keyboard is 11 inches longer than it is wide. If the length were doubled and if 2 inches were added to the width the area would increase by 198 sq inches. What are the length and width of the keyboard?
Answer by TimothyLamb(4379)   (Show Source):
You can put this solution on YOUR website! ---
x = y + 11
2x(y + 2) = xy + 198
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2x(y + 2) = xy + 198
2xy + 4x = xy + 198
xy + 4x = 198
x(y + 4) = 198
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x(y + 4) = 198
(y + 11)(y + 4) = 198
yy + 15y + 44 = 198
yy + 15y - 154 = 0
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the above quadratic equation is in standard form, with a=1, b=15, and c=-154
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to solve the quadratic equation, by using the quadratic formula, copy and paste this:
1 15 -154
into this solver: https://sooeet.com/math/quadratic-equation-solver.php
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this quadratic has two real roots (the x-intercepts), which are:
y = 7
y = -22
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negative width doesn't make sense for this problem, so use the positive root
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y = width = 7 inches
x = length = 18 inches
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Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
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Solve systems of linear equations up to 6-equations 6-variables:
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