Engineering Board Exam Reviewer · Logarithms · hard

Solve 2x+ x2= 52.

1. x=4 or x=2
2. x=2 or x= 2
3. x=4 or x= 2
4. x=4 or x= 14

Answer

C. x=4 or x= 2

Solution

Let u= 2x, so x2= 1u: u+ 1u= 52 2u2-5u+2=0 u=2 or 12. Then x=22=4 or x=21/2= 2.

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