If 3x + 1/2x = 5, find the value of 9x^2 + 1/4x^2.

22. Square: 9x^2 + 2 · 3x · 1/2x + 1/4x^2 = 25, and the middle term is 3. So the value is 25 - 3 = 22.

If $3 x + \frac{1}{2 x} = 5$ , find the value of $9 x^{2} + \frac{1}{4 x ^{2}}$ .

Competition practiceAlgebra

Square:

9 x^{2} + 2 \cdot 3 x \cdot \frac{1}{2 x} + \frac{1}{4 x ^{2}} = 25

, and the middle term is 3. So the value is

25 - 3 = 22

Answer: C) 22

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