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ESO Y4B · Mathematics
Equations and systems · Equations, inequalities and systems

Other types of equations

Not every equation that "looks difficult" really is. Many of them can be turned, with the right trick, into a linear or quadratic equation that you already know how to solve. The key is to spot the trick: a change of variable, clearing denominators, isolating a root or using the definition of a logarithm.

Before you start, make sure you know: Quadratic equations (3rd ESO)
Before you start, make sure you know: Special products (2nd ESO)

Biquadratic equations

Diagram of the substitution $t = x^2$ for solving a biquadratic equation and the calculation of the four solutions when undoing the substitution with $x = \pm\sqrt{t}$. x⁴ − 10x² + 9 = 0 t² − 10t + 9 = 0 t = x² t = 1, t = 9 x = ±1, x = ±3 x = ±√t
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Solve the following biquadratic equation using the substitution $x^2 = t$: $x^4 - 10x^2 + 9 = 0$

Solve the following biquadratic equation using the substitution $x^2 = t$:

$x^4 - 10x^2 + 9 = 0$

Solve
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Find all real solutions to the following incomplete biquadratic equation by taking out a common factor: $2x^4 - 32x^2 = 0$

Find all real solutions to the following incomplete biquadratic equation by taking out a common factor:

$2x^4 - 32x^2 = 0$

Solve
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Solve the following biquadratic equation and state clearly which of its solutions are real and why the others are discarded: $x^4 - 2x^2 - 8 = 0$

Solve the following biquadratic equation and state clearly which of its solutions are real and why the others are discarded:

$x^4 - 2x^2 - 8 = 0$

Solve

Rational equations

Diagram of the procedure for solving rational equations: find the forbidden values of the domain, multiply by the lowest common multiple of the denominators and discard invalid solutions. x/(x−2) + 2x/(x+2) = 16/(x²−4) denominators = 0 when x = 2 or x = −2 these values are always outside the domain
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Solve the following rational equation by multiplying all terms by $x$ to clear the denominator: $\frac{12}{x} = x - 4$

Solve the following rational equation by multiplying all terms by $x$ to clear the denominator:

$\frac{12}{x} = x - 4$

Solve
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Find the value of $x$ that satisfies the following simple rational equation: $\frac{x+3}{x-1} = 2$

Find the value of $x$ that satisfies the following simple rational equation:

$\frac{x+3}{x-1} = 2$

Solve
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Solve the following rational equation by finding a common denominator. Pay special attention to possible solutions that make any denominator zero:…

Solve the following rational equation by finding a common denominator. Pay special attention to possible solutions that make any denominator zero:

$\frac{x}{x-2} + \frac{3}{x+2} = \frac{8}{x^2-4}$

Solve

Irrational equations

Steps for solving an irrational equation: isolate the square root, square both sides and simplify to a quadratic equation. √(2x+7) = x + 2 2x+7 = x²+4x+4 ( )² ⇒ x² + 2x − 3 = 0
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Solve the radical equation by isolating the square root and squaring both sides: $\sqrt{3x + 4} = 5$

Solve the radical equation by isolating the square root and squaring both sides:

$\sqrt{3x + 4} = 5$

Solve
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Determine the values of $x$ that satisfy the following radical equation. Remember that you must check the solutions at the end to rule out any false solutions:…

Determine the values of $x$ that satisfy the following radical equation. Remember that you must check the solutions at the end to rule out any false solutions:

$\sqrt{x + 2} = x$

Solve
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Solve the radical equation by isolating one of the square roots and squaring. Remember to check the solution obtained: $\sqrt{x+4} - \sqrt{x-1} = 1$

Solve the radical equation by isolating one of the square roots and squaring. Remember to check the solution obtained:

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

Solve

Exponential and logarithmic equations

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Solve the following exponential equation by expressing both sides as powers of the same base: $3^{2x-1} = 27$

Solve the following exponential equation by expressing both sides as powers of the same base:

$3^{2x-1} = 27$

Solve
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Find the value of $x$ in the logarithmic equation by directly applying the definition of a logarithm: $\log_2(x + 5) = 3$

Find the value of $x$ in the logarithmic equation by directly applying the definition of a logarithm:

$\log_2(x + 5) = 3$

Solve
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The number of members on a Discord server follows the exponential formula $N = 500 \cdot 2^{t/3}$, where $t$ is the time elapsed in months. How many months must pass for…

The number of members on a Discord server follows the exponential formula $N = 500 \cdot 2^{t/3}$, where $t$ is the time elapsed in months. How many months must pass for the server to reach exactly $4000$ members?

Solve

Summary

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