Q. The length of an 8000 square foot rectangular gymnasium is 20 feet greater than its width. What is its width, in feet?◻
Define Variables: Let's denote the width of the gymnasium as w (in feet). According to the problem, the length is 20 feet greater than the width, so we can denote the length as w+20. The area of a rectangle is given by the product of its length and width, so we can set up the equation w×(w+20)=8000 to find the width.
Set Up Equation: Now we need to solve the quadratic equationw2+20w−8000=0. This is a standard quadratic equation in the form of aw2+bw+c=0, where a=1, b=20, and c=−8000.
Solve Quadratic Equation: To solve the quadratic equation, we can use the quadratic formulaw=2a−b±b2−4ac. Plugging in the values, we get w=2⋅1−20±202−4⋅1⋅(−8000).
Calculate Discriminant: Calculating the discriminant b2−4ac gives us 202−4⋅1⋅(−8000)=400+32000=32400. Taking the square root of 32400 gives us 32400=180.
Substitute Values: Substituting the values back into the quadratic formula, we get w=(−20±180)/2. This gives us two possible solutions for w: w=(−20+180)/2 or w=(−20−180)/2.
Calculate Possible Solutions: Calculating the two possible values for w, we get w=2160=80 for the first solution and w=2−200=−100 for the second solution. Since a width cannot be negative, we discard the second solution.
Identify Correct Width: Therefore, the width of the gymnasium is 80 feet.
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