问题1.在R中求解以下每个方程组：x + 3> 0，2x <14
解决方案：
Let the first equation be x+3>0
⇒ x > -3
and the second equation be 2x < 14
⇒ x < 7
Hence, using above equations, we know x lies in range (-3,7)
问题2.在R中求解以下每个方程组：2x – 7> 5 – x，11 – 5x≤1
解决方案：
Let the first equation be 2x – 7 > 5 – x
⇒ 3x > 12
⇒ x >4
and the second equation be 11 – 5x ≤ 1
⇒ 10 ≤ 5x
⇒ 2 ≤ x
Hence, using above equations, we know x lies in range (4,∞)
问题3.在R中求解以下每个方程组：x – 2> 0，3x <18
解决方案：
Let the first equation be x – 2 > 0
⇒ x > 2
and the second equation be 3x < 18
⇒ x < 6
Hence, using above equations, we know x lies in range (2,6)
问题4.在R中求解以下每个方程组：2x + 6≥0，4x – 7 <0
解决方案：
Let the first equation be 2x+6 ≥ 0
⇒ 2x ≥ -6
⇒ x ≥ -3
and the second equation be 4x – 7< 0
⇒ 4x < 7
⇒ x < 7/4
Hence, using above equations, we know x lies in range [-3, 7/4)
问题5.在R中求解以下每个方程组：3x – 6> 0，2x – 5> 0
解决方案：
Let the first equation be 3x – 6 > 0
⇒ 3x > 6
⇒ x > 2
and the second equation be 2x – 5> 0
⇒ 2x > 5
⇒ x > 5/2
Hence, using above equations, we know x lies in range (5/2, ∞)
问题6.在R中求解以下每个方程组：2x – 3 <7，2x> -4
解决方案：
Let the first equation be 2x – 3 < 7
⇒ 2x < 10
⇒ x < 5
and the second equation be 2x > – 4
⇒ x > -2
Hence, using above equations, we know x lies in range (-2, 5)
问题7：在R中求解以下每个方程组：2x + 5≤0，x – 3≤0
解决方案：
Let the first equation be 2x + 5 ≤ 0
⇒ 2x ≤ -5
⇒ x ≤ -5/2
and the second equation be x – 3 ≤ 0
⇒ x ≤ 3
Hence, using above equations, we know x lies in range (-∞, -5/2]
问题8.在R中求解以下每个方程组：5x – 1 <24，5x +1> -24
解决方案：
Let the first equation be 5x – 1 < 24
⇒ 5x < 25
⇒ 5x < 25
⇒ x < 5
and the second equation be 5x + 1 > -24
⇒ 5x > -25
⇒ x > -5
Hence, using above equations, we know x lies in range (-5, -5)
问题9.在R中求解以下每个方程组：3x – 1≥5，x + 2> -1
解决方案：
Let the first equation be 3x – 1 ≥ 5
⇒ 3x ≥ 6
⇒ x ≥ 2
and the second equation be x + 2 > -1
⇒ x > -3
Hence, using above equations, we know x lies in range [2, ∞)
问题10：在R中求解以下每个方程组：11 – 5x> -4，4x + 13≤-11
解决方案：
Let the first equation be 11 – 5x > -4
⇒ 15 > 5x
⇒ x < 3
and the second equation be 4x + 13 ≤ -11
⇒ 4x ≤ -24
⇒ x ≤ -6
Hence, using above equations, we know x lies in range (-∞, -6]