Question

Выполните действия:
б) - 2,75 × (-0,1)^2 × (- 3 7/11)
Найдите корень уравнения:
x|x| = - 4 |x|

Answer 1

б) -2,75*(-0,1)^2*(3 7/11) = 0,1
1) (-0,1)^2 = (-0,1)*(-0,1) = 0,01
2) -2,75*0,01 = -0,0275 = - 11/400
3) (-11/400)*(-3 7/11) = (-11/400)*(-40/11) = $\frac{11*40}{400*11}$ = 0,1

$x|x|=-4|x| <=> \left[ \left \{ {{x>0} \atop {x^2=-4x}} \right. \left \{ {{x<0} \atop {-x^2=4x}}\right.<=>\left[ \left \{ {{x>0} \atop {x^2+4x=0}} \right.\left \{ {{x<0} \atop {-x^2-4x=0}} \right.$$<=> \left \{ {{x<0} \atop {x^2+4x=0}} \right. <=> \left \{ {{x<0} \atop {x(x+4)=0}} \right. <=> \left \ {{x=0} \atop {x=-4}} \right. \\ Otvet: -4; 0$