Question

.1) 7x - 21 < 0,1 - x > 0;2)25 - 5 x > 0,3x – 18 < 0;3)(1,2 - 0,6 x > 0,9x + 27 < 0.​

Answer 1

Ответ:

Пошаговое объяснение:

1)

7x-21<0; 7x<21; x<21/7; x<3; x∈(-∞; 3)

1-x>0; x<1; x∈(-∞; 1)

Если эта система неравенств, тогда ответ такой: x∈(-∞; 1).

2)

25-5x>0; 5x<25; x<25/5; x<5; x∈(-∞; 5)

3x-18<0; 3x<18; x<18/3; x<6 x∈(-∞; 6)

Если эта система неравенств, тогда ответ такой: x∈(-∞; 5).

3) 1,2-0,6x>0; 0,6x<1,2; x<12/6; x<2; x∈(-∞; 2)

9x+27<0; 9x<-27; x<-27/9; x<-3; x∈(-∞; -3)

Если эта система неравенств, тогда ответ такой: x∈(-∞; -3).

Answer 2

To solve the given system of inequalities, we'll go through each one step by step.

1. $7x - 21 < 0$ and $1 - x > 0$:

Solving $7x - 21 < 0$: $7x < 21$ $x < 3$

Solving $1 - x > 0$: $1 > x$ $x < 1$

So, for the first set of inequalities, the solution is $x < 1$ and $x < 3$, which means the solution is $x < 1$.

2. $25 - 5x > 0$ and $3x - 18 < 0$:

Solving $25 - 5x > 0$: $5x < 25$ $x < 5$

Solving $3x - 18 < 0$: $3x < 18$ $x < 6$

For the second set of inequalities, the solution is $x < 5$ and $x < 6$, which means the solution is $x < 5$.

3. $1.2 - 0.6x > 0$ and $0.9x + 27 < 0$:

Solving $1.2 - 0.6x > 0$: $-0.6x > -1.2$ $x < 2$

Solving $0.9x + 27 < 0$: $0.9x < -27$ $x < -30$

For the third set of inequalities, the solution is $x < -30$ and $x < 2$. Since $x < 2$ includes $x < -30$, we can just say $x < 2$ is the solution.

In summary, the solution to the system of inequalities is $x < 1$ and $x < 5$ and $x < 2$. The combined solution is $x < 1$.