Let's go through each problem step by step.
Solve the inequalities:
- \(\frac{1}{2}x - 5 - 0.2 \times 3x - x^2 \geq 0\):
Let's simplify and solve the expression: \[ \frac{1}{2}x - 0.6x - x^2 - 5 \geq 0 \]
Simplify: \[ -0.1x - x^2 - 5 \geq 0 \]
This is a quadratic inequality. Consider finding the roots and analyzing intervals if needed.
- \(3.6x + 1 > 0\):
\[ 3.6x > -1 \\ x > -\frac{1}{3.6} \]
Solve the inequalities using interval method:
\((1) \, (x+3)(x+7) \leq 0\)
Find roots:
- \(x + 3 = 0 \Rightarrow x = -3\)
- \(x + 7 = 0 \Rightarrow x = -7\)
The intervals to test are \((-\infty, -7)\), \([-7, -3]\), and \((-3, \infty)\).
Solve the equation:
\((2) \, 5 + 4 \cdot \frac{9z - 2}{z} = 0\)
Simplify and solve for \(z\): \[ 5 + \frac{36z - 8}{z} = 0 \\ 5z + 36z - 8 = 0 \\ 41z = 8 \\ z = \frac{8}{41} \]
Find the values where the expression has meaning:
\(\frac{\sqrt{x+3} - 5}{x^2 - 9x + 2}\)
Ensure the denominator is not zero: \[ x^2 - 9x + 2 \neq 0 \]
Solve the quadratic \(x^2 - 9x + 2 = 0\) using the quadratic formula if needed.
Find the domain of the function:
\(y = \frac{1}{\sqrt{x^3}}\)
Ensure the expression under the square root is non-negative and not zero: \[ x^3 > 0 \rightarrow x > 0 \]
If specific calculations are needed for the quadratic solutions, apply the quadratic formula \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\). Let me know if you need calculations for any specific part!