Equation facts for kids

An equation is a math statement that shows two things are exactly equal. It uses an equals sign (=) to connect them. This sign means that what's on one side is the same value as what's on the other side. An equation can be super simple, like x=0, or much more complex, like .

There are two main kinds of math equations:

• Some equations are always true, no matter what. These are also called identities. For example:

 :Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): 2 \cdot (x+4)=2x+8 is always true.

• Other equations are only true for certain values of a variable (a letter like 'x' or 'y'). The equation only works if the variable has that specific value. For example:

 : Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): 2 \cdot x=8 is only true if Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): x=4 .

The second type of equation is often used to solve problems. You use them to find the missing value of one or more variables. For instance, if you have Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): 2x = 8 , you can figure out that Failed to parse (Missing <code>texvc</code> executable. Please see math/README to configure.): x = 4 .

This second kind of equation is a big part of algebra. Algebra gives us rules to find the unknown values in equations.

Types of Equations

Equations can be grouped based on the kinds of math operations and numbers they involve.

Algebraic Equations

An algebraic equation is one where both sides are polynomials. A polynomial is a math expression with variables and numbers, using only addition, subtraction, multiplication, and whole number exponents. These equations are also sorted by their "degree," which is the highest power of the variable in the equation.

• Linear equation: This is an equation where the highest power of the variable is one (like `x`).
• Quadratic equation: Here, the highest power of the variable is two (like `x²`).
• Cubic equation: The highest power of the variable is three (like `x³`).
• Quartic equation: The highest power of the variable is four (like `x⁴`).
• Quintic equation: The highest power of the variable is five (like `x⁵`).

Diophantine Equations

A Diophantine equation is a special type of equation where you are only looking for integer (whole number) answers for the unknowns.

Related pages

• Equation solving
• Formula
• Rate equation
• System of linear equations

Images for kids

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  The first time an equals sign was used. It meant 14x + 15 = 71 in today's math. This was from a book called The Whetstone of Witte by Robert Recorde in 1557.

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  The Nine Chapters on the Mathematical Art is an old Chinese book from the 2nd century. It showed ways to solve linear equations.

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  A conic section is a shape you get when you slice through a cone with a flat surface.

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  A strange attractor, which is a complex pattern that comes from solving a certain type of equation called a differential equation.

See also

In Spanish: Ecuación para niños