Question

If 5x + x² > 100, then x is not 10 8 7 9

Answer 1

We will solve the equation:
x^2+5x-100≥0 $x_{12} = \frac{-5\pm \sqrt{25+400} }{2}= \frac{-5\pm20.6}{2}$      x1≈-12.8   x2≈ 7.8
It means that x∈ (-∞, -12.8 ) ∪ (7.8, +∞ ).
Answer: C) x ≠ 7
Thank you.