решите уравнение (х-4)(4х-3)+3=0

(х - 4) * (4 * х - 3) + 3 = 0; 

Раскроем скобки. 

x * 4 * x - 3 * x - 4 * 4 * x + 4 * 3 + 3 = 0; 

4 * x^2 - 3 * x - 16 * x + 12 + 3 = 0; 

4 * x^2 - x * (3 + 16) + 15 = 0; 

4 * x^2 - 19 * x + 15 = 0; 

D = b^2 - 4 * a * c = (-19)^2 - 4 * 4 * 15 = 361 - 16 * 15 = 361 - 240 = 121 = 11^2; 

x1 = (19 + 11)/(2 * 4) = 30/8 = 15/4; 

x2 = (19 - 11)/8 = 8/8 = 1; 

Ответ: х = 1 и х = 15/4.