Question 1029036
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A picture is 4cm by 6cm. it is pasted onto a matte of equal width on all sides. What is the width of the matte 
if the area of the matte is 3 times as great as the area of the picture?
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Your guiding equation is

(2x+4)*(2x+6) = 3*4*6,   or

(2x+4)*(2x+6) = 72,

{{{4x^2 + 8x + 12x + 24}}} = {{{72}}},

{{{4x^2 + 20x - 48}}} = {{{0}}},

{{{x^2 + 5x - 12}}} = {{{0}}}.

Use the quadratic formula and get

x = {{{(sqrt(73)-5)/2}}}.
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