1/Find the length x if the shaded area is 420 cm 2 . x = cm ....................

Question

1/Find the length x if the shaded area is 420 cm2.

x =  cm

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2/A parcel of land is 8 ft longer than it is wide. Each diagonal from one corner to the opposite corner is 232 ft long. What are the dimensions of the parcel?

ft

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3/ A telephone company offers two long-distance plans.

Plan A: $25 per month and 5¢ per minute
Plan B:  $3 per month and 14¢ per minute

For how many minutes of long-distance calls would plan B be financially advantageous? (Assume the plan will be used for one month. Round your answer up to the nearest whole minute.)

Plan B is advantageous if a person places fewer than( )minutes of long-distance calls during a month.

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ft

Explanation / Answer

Solution:

the shaded area is 420 cm2.

Now area of shaded portion = Area of rectangle + area of triangle

= length x width + 1/2 (base ) height

= x *1 + 1/2 ( x) (x)

= x + (1/2) x2

x + (1/2) x2 = 420

x2 + 2x =840

x2 + 2x -840 = 0

(x+30) (x-28) =0

Now x = -30 and x = 28

we take positive value x =28

therefore x = 28

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