It is proved that: - 10x2 + 7x-4 is less than 0

It is proved that: - 10x2 + 7x-4 is less than 0

It is proved that: - 10x2 + 7x-4 = - 10 (x2-70x) - 4 = - 10 (x-720) 2-11140, ∵ (x-720) 2 ≥ 0, ∵ (x-720) 2 ≤ 0, ∵ - 10 (x-720) 2-11140 < 0