Question

Помогите решить пожалуйста!

Answer 1

8)

$\frac{x+4}{7}- \frac{x+7}{4} \ \textgreater \ -3 \\ \frac{4(x+4)-7(x+7)}{28} \ \textgreater \ -3 \\ \frac{4x+16-7x-49}{28} \ \textgreater \ -3 \\ \frac{-3x-33}{28} +3 \ \textgreater \ 0 \\ \frac{-3x-33+84}{28} \ \textgreater \ 0 \\ \frac{-3x+51}{28} \ \textgreater \ 0 \\ -3x+51\ \textgreater \ 0 \\ -3x\ \textgreater \ -51 \\ x\ \textless \ 17$

Ответ:E)

$(-oo;17)$

9)

$\left \{ {{x-y=16} \atop { \sqrt{x} - \sqrt{y} =2}} \right. \\ \left \{ {{x-y=16} \atop { \sqrt{x^2} =(2+ \sqrt{y})^{2} } \right. \\ \left \{ {{x-y=16} \atop { x} =4+4 \sqrt{y}+y } \right \\ \left \{ {{4+4 \sqrt{y}+y-y=16} \atop { x} =4+4 \sqrt{y}+y } \right \\ \left \{ {{4+4 \sqrt{y}=16} \atop { x} =4+4 \sqrt{y}+y } \right \\\right \\ \left \{ {{4 \sqrt{y}=12} \atop { x} =4+4 \sqrt{y}+y } \right \\ \left \{ {{\sqrt{y}=3} \atop { x} =4+4 \sqrt{y}+y } \right$

$\left \{ {{y=9} \atop {x=4+4 \sqrt{y} +y}} \right. \\ \left \{ {{y=9} \atop {x=4+4 \sqrt{9} +9}} \right. \\ \left \{ {{y=9} \atop {x=4+12 +9}} \right. \\ \left \{ {{y=9} \atop {x=25}} \right.$

Ответ:А) (25;9)

10)

$x^2-3x+2=x^2-x-2x+2=x(x-1)-2(x-1)=(x-1)(x-2);$

Ответ:В)