Question

What is the value of x (distance from the edge of the screen to the end of the wall) if the area of the screen is 40 m^2?

Answer 1

The value of x that is the length from the edge of the screen to the end of the wall is equal 3. This is derived from an equation which serves as a function of the Area. See the solution below.

What is the calculation for the solution above?

Recall that the area of the entire wall is 40m².

(10-2x) (16- 2x) = 40

Expanding the brackets, we have

160-20x-32x + 4x² = 40
4x² - 52x + 120 = 0
x² - 13x +30 = 0

Using the quadratic equation

x = (-b±√b²-4ac)/2a

Where a = 1
b  = 13
c = 30

x = (13 ± 7)/2

Thus x = 10; or x = 3.

x cannot be the answer because it invalidates 16-x<0;

Hence, the correct answer is x = 3

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