Bunuel
The mean of three numbers \(2x\), \(3x\), \(x^2\) is \(12\), where \(x<0\). What is the range of the three numbers?
A. 108
B. 144
C. 176
D. 228
E. 256
Let's set up the equation based on the given information:
The mean of three numbers 2x, 3x, and x^2 is 12.
The mean is calculated by adding up all the numbers and then dividing by the total count. In this case:
(2x+3x+x^2)/3=12
Now, solve for x:
(5x+x^2)/3=12
Multiply both sides by 3 to get rid of the fraction:
5x+x^2=36
Combine like terms:
x^2+5x−36=0
Now, factor the quadratic equation:
(x−4)(x+9)=0
So, the solutions for x are x = 4 and x = -9. Since it's given that x < 0, we discard the x = 4 solution.
Now, the three numbers are 2x, 3x, and x^2. We can find these for x = -9:
2(−9)=−18
3(−9)=−27
(−9)^2=81
So, the three numbers are -18, -27, and 81.
Now, to find the range, subtract the smallest from the largest:
81−(−27)=108
Therefore, the range of the three numbers is 108.