5х³ + 19х² - 38х - 40 = 0;
5х³ -10х² + 29х² - 58х + 20х - 40 = 0;
(5х³ -10х²) + (29х² - 58х) + (20х - 40) = 0;
5х²(х -2) + 29х(х -2) + 20(х - 2) = 0;
(х -2)(5х² + 29х + 20) = 0;
х -2 = 0
х = 2.
или
5х² + 29х + 20 = 0
Д = 841 - 4*5*20 = 841 - 400 = 441 = 21².
х₁ = (-29 + 21)/10 = -0,8;
х₂ = (-29 - 21)/10 = -5.
ОТВЕТ: -5; -0,8; 2.
a(a + 5b) - (a + b)(a - b)=a^2+5ab-a^2+b^2=5ab+b^2
b(3a-b) - (a - b)(a + b)=3ab-b^2-a^2+b^2=3ab-a^2
(y+10)(y-2)-4y(2 - 3y)=y^2+8y-20-8y+12y^2=13y^2-20
(a-4)(a+9)-5a(1-2a)=a^2+5a-36-5a+10a^2=11a^2-36
(2b-3)(3b+2)-3b(2b+3)=6b^2-9b+4b-6-6b^2-9b=-14b-6
(3a-1)(2a-3)-2a(3a+5)=6a^2-2a-6a+4-6a^2-10a=-18a+4
(m+3)^2 -(m-2)(m+2)=m^2+6m+9-m^2+4=5m+13
(a-1)^ - (a+1)(a-2)=a^2-2a+1-a^2-a-2=-3a-1
(c+2)(c-3)-(c-1)^2=c^2-c-6-c^2+2c-1=c-7
(y-4)(y+4)-(y-3)^=y^2-16-y^2+6y-9=6y-25
(a-2)(a+4)-(a+1)^ =a^2+2a-8-a^2-2a-1=-9
(b-4)(b+2)-(b-1)^=b^2-2b-8-b^2+2b-1=-9
Думаю так
