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Advanced Math / Nonlinear functions Difficulty: Hard

The area of a triangle is equal to x 2 square centimeters. The length of the base of the triangle is 2 x + 22 centimeters, and the height of the triangle is x - 10 centimeters. What is the value of x ?

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Explanation

The correct answer is 110. The area of a triangle is equal to one half of the product of the length of the base of the triangle and the height of the triangle. It's given that the length of the base of the triangle is 2x+22 centimeters and the height of the triangle is x-10 centimeters; therefore, its area is 12(2x+22)(x-10) square centimeters. It's also given that the area of the triangle is equal to x2 square centimeters. Therefore, it follows that 12(2x+22)(x-10)=x2.  This equation can be rewritten as (x+11)(x-10)=x2, or x2+x-110=x2. Subtracting x2 from both sides of this equation yields x-110=0. Adding 110 to both sides of this equation yields x=110. Therefore, the value of x is 110.