10x^2-25x>0
1) Let's solve in ℝ: 10x2 -25x > 0
You can factorize the expression: 10x2 -25x into: x·(10x -25)
We study the sign of each factor of the product
⇥The expression x is zero at x = 0, it is negative before and positive after
⇥The expression 10x -25 is zero at:
⇥ x = 2510
⇥ⓘ We simplify the fraction by dividing the numerator and the denominator by 5, their greatest common divisor: 2510 = 5·52·5 = 52
⇥ x = 52
⇥Its coefficient of x, 10, being positive, it is negative before and positive after 52
2) Let's draw up the sign table:
x-∞ 0 52 +∞
x-0++
10x -25--0+
10x2 -25x+0-0+
▶Solution obtained: x ∈ (-∞, 0) ∪ (52, +∞)
3) The numeric value of: x ∈ (-∞, 0) ∪ (52, +∞) is:
▷ x ∈ (-∞, 0) ∪ (2.5, +∞)