If x > 0, What is the least possible value of -2√(5x) + x + 9 ?
A. 0
B. 1
C. √5
D. 4
E. 9
OA D
Source: e-GMAT
If x > 0, What is the least possible value of -2√(5x) +
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Notice that (√x - √5)^2 = (√x)^2 + (√5)^2 - 2(√x)(√5) = x + 5 - 2√(5x). Therefore,BTGmoderatorDC wrote:If x > 0, What is the least possible value of -2√(5x) + x + 9 ?
A. 0
B. 1
C. √5
D. 4
E. 9
OA D
Source: e-GMAT
-2√(5x) + x + 9 = (√x - √5)^2 + 4
Since the minimum value of (√x - √5)^2 is 0, then the minimum value of -2√(5x) + x + 9 is:
(√x - √5)^2 + 4 = 0 + 4 = 4
Answer: D
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