3\4x-20+15\50-2x^2+7\6x+30=0

неверно

2x+4x=30
6x=30
x=30:6
x=5
ответ5

2x^2+7x-4 больше 0 2x2 + 7x - 4 = 0
D = b2 - 4ac
D = 49 + 32 = 81 = 9^2x1,2 = -b ± √D/2a
x1 = -7 + 9/4 = 2/4 = 1/2
x2 = -7 - 9/4 = - 16/4 = -4
Ответ: x1 = 1/2 ; x2 = -4 (-4;0,5)