Question 1187206
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the dimension of rectangular metal box are 3cm 5cm and 8 cm. 
if the first 2 dimension are increased by the same numbers of centimeters, 
while the 3rd dimension remains the same, the new volume is 34cmcube more 
than the original volume. what is the new dimension of the enlarged rectangular metal box?
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Let x be the linear increment.


Then you have this equation (write as you read the problem)

    (3+x)*(5+x)*8 - 3*5*8 = 34  cubic centimeters.


Make FOIL and simplify

    (15 + 8x + x^2)*8 - 120 = 34

     120 + 64x + 8x^2 - 120 = 34

     8x^2 + 64x - 34 = 0.


Find the roots using the quadratic formula and select the positive root, which is x = 0.5 cm.


<U>ANSWER</U>.  The new dimensions are  3.5 cm, 5.5 cm and 8 cm.
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Solved.