document.write( "Question 1186790: All edges of a cube are expanding at a rate of 5 centimeters per second.\r
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Algebra.Com's Answer #817761 by math_helper(2461) $\"\"$ $\"About$

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document.write( "These are related-rates problems.\r
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document.write( "(a)
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document.write( "The surface area of a cube of side a is:
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document.write( "S =   \r
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document.write( "The rate of change of surface area, with respect to t, is:
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document.write( " = \r
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document.write( " = 12a 
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document.write( " = 5cm/s   (given)\r
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document.write( "So we can write:
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document.write( " =  =     (*)\r
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document.write( "So at a=3cm, the surface area is changing at 
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document.write( " = 12(3)cm * 5cm/s = 180 \r
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document.write( "(b) plug a=10cm  into (*)  \n" );
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