Exercises: Radical equations

Solve the following radical equation and check the validity of the solution obtained:

$\sqrt{3x - 2} = 4$

Determine the value of $x$ satisfying the following irrational equation:

$\sqrt{2x + 7} - x = 2$

Solve the following equation containing a higher-order root:

$\sqrt[3]{5x - 4} = -1$

Find the solution to the equation by equating both radicals and check the result:

$\sqrt{x + 5} = \sqrt{3x - 1}$

The time $t$ (in seconds) taken for an object to fall freely from a height $h$ (in meters) is given by the physics formula $t = \sqrt{\frac{2h}{9.8}}$. Calculate the height from which a stone was dropped if it took exactly $3$ seconds to reach the ground.

Find the values of $x$ satisfying the following equation with fractions inside the radicand:

$\sqrt{\frac{4x - 1}{3}} = 5$

The base radius $r$ of a cylinder of volume $V$ and height $h$ is calculated using the expression $r = \sqrt{\frac{V}{\pi h}}$. If a cylindrical container of height $15\text{ cm}$ has a volume of $471\text{ cm}^3$, set up the corresponding equation and find its base radius (use the approximation $\pi \approx 3.14$).

Solve the following radical equation and explain why one of the potential algebraic solutions obtained after squaring is invalid:

$x - \sqrt{x + 1} = 5$

Solve the following irrational equation containing two radicals:

$\sqrt{x + 4} - \sqrt{x - 1} = 1$

Calculate the $x$-coordinate where a point $P(x, 4)$ must be placed relative to point $A(-2, 1)$ so that the Euclidean distance between them is exactly $5$ units. Set up the corresponding radical equation using the distance formula and solve it.

The production cost $C$ (in thousands of pesos) of manufacturing $x$ units of a high-precision electronic component follows the mathematical model $C(x) = 12 + \sqrt{5x + 4}$. If the exact budget allocated for the production of this batch is $25$ thousand pesos, how many units can be manufactured?

Find the real solutions to the following irrational equation by properly isolating one of the radicals before squaring:

$\sqrt{2x - 1} + \sqrt{x + 4} = 6$

The period $T$ of oscillation of a simple pendulum (in seconds) is related to its length $L$ (in meters) by the physical expression $T = 2\pi \sqrt{\frac{L}{g}}$. Taking the acceleration due to gravity as $g \approx \pi^2\text{ m/s}^2$, set up the equation and find the length of a pendulum whose period of oscillation is exactly $2.5$ seconds.

Find the real solutions to the following equation containing a nested radical (a radical inside another):

$\sqrt{x + \sqrt{x + 3}} = 3$

Solve the following irrational equation. It will be easier if you use a suitable substitution, for example $t = \sqrt{x^2 - 2}$:

$x^2 - 3\sqrt{x^2 - 2} = 6$

In an architectural project, an access ramp is designed resting against a vertical wall $12\text{ m}$ high. The length of the ramp is $\sqrt{x^2 + 144}$ and the horizontal distance from the start of the ramp to the base of the wall is $x$. If, due to safety and gradient regulations, the ramp must measure exactly $4\text{ m}$ more than the horizontal distance $x$, set up and solve the irrational equation to find $x$.

Solve the following irrational equation containing three radicals. Take special care when collecting terms after squaring for the first time:

$\sqrt{x + 2} + \sqrt{x - 3} = \sqrt{3x + 4}$

A fiber-optic cable must connect two communications towers $A$ and $B$ of heights $15\text{ m}$ and $20\text{ m}$ respectively, passing through an anchor point $P$ located on the ground between both towers. The horizontal distance between the towers is $35\text{ m}$. If point $P$ is located $x$ meters from tower $A$, the total length of the cable is given by $L = \sqrt{x^2 + 225} + \sqrt{(35 - x)^2 + 400}$. If exactly $50\text{ m}$ of cable is available and is to be used in its entirety without cuts, determine at what distance $x$ the anchor $P$ should be placed.

Determine the numerical value of the parameter $k$ so that the irrational equation $\sqrt{x + k} = x - 1$ has a single valid real solution of multiplicity one. Justify your answer by analysing the discriminant of the resulting quadratic equation and the validity conditions of the radical.

Solve the following equation, which combines the properties of absolute values with irrational expressions. Carefully consider the cases for the absolute value:

$|\sqrt{3x + 1} - 4| = 2$

Solve the following irrational equation with roots of different indices. It will be very helpful to perform the substitution $t = \sqrt[6]{x}$:

$\sqrt{x} - 7\sqrt[3]{x} + 12\sqrt[6]{x} = 0$

Special relativity establishes that the relativistic mass $m$ of a moving object is given by the equation $m = \frac{m_0}{\sqrt{1 - \frac{v^2}{c^2}}}$, where $m_0$ is the rest mass, $v$ is the velocity of the object and $c$ is the speed of light in a vacuum. Rearrange algebraically to find the velocity $v$ in terms of $m$, $m_0$ and $c$. Subsequently, calculate at what fraction of the speed of light $c$ a spacecraft must travel for its relativistic mass to be exactly double its rest mass.

Analyse and solve the following non-linear system of equations involving radicals. You can exploit the algebraic structure of the second equation (difference of two squares) to simplify the process:

$\begin{cases} \sqrt{x} + \sqrt{y} = 5 \\ x - y = 5 \end{cases}$

Prove algebraically and with reasoning why the irrational equation $\sqrt{x - 4} + \sqrt{2 - x} = 5$ has no solutions in the set of real numbers. Base your proof on the analysis of the domain of definition of the radicals involved, without needing to square both sides.