3а-15b=3*(-3/4)-15*0,8=3*(-0,75)-15*0,8=-2,25-12=-14,25
Х^2 + 7х + 10
1) х^2 + 7х + 10 = 0
D = 49 - 40 = 9 = 3^2. X1 = ( - 7 + 3 ) : 2 = - 2
X2 = ( - 7 - 3 ) : 2 = - 5
Ответ : - 2 ; - 5
2) х^2 + 7х + 10 = 4
Х^2 + 7х + 6 = 0
D = 49 - 24 = 25 = 5^2
X1 = ( - 7 + 5 ) : 2 = - 1
X2 = ( - 7 - 5 ) : 2 = - 6
Ответ : - 1 ; - 6
3) х^2 + 7х + 10 = - 1
Х^2 + 7х + 11 = 0
D = 49 - 44 = 5
X1 = ( - 7 + V 5 ) : 2 = - 3,5 + 0,5V5
X2 = ( - 7 - V 5 ) : 2 = - 3,5 - 0,5V5
7+4x=5x+9
4x-5x=9-7
-x=2 |*(-1)
x=-2
1.a)f'(x)=(x5)=4x3
б)f'(x)=0
в)f'(x)=(4/x)'=x-4/x2
г)f'(x)=-2
д)f'(x)=1/х+3cosx