Which of the following is a linear equation in one variable?

$x+5=12$

$x^2=25$

$y+z=10$

$x-3<7$

Verified step by step guidance

Recall that a linear equation in one variable is an equation where the variable is raised only to the first power and appears in a form like $ax + b = c$, where $a$, $b$, and $c$ are constants.

Look at each option and identify the variable and its exponent or form:

For $x + 5 = 12$, the variable $x$ is to the first power, and the equation fits the form $ax + b = c$.

For $x^2 = 25$, the variable $x$ is squared (raised to the second power), so this is not linear.

For $y + z = 10$, there are two variables, so it is not an equation in one variable.

For $x - 3 < 7$, this is an inequality, not an equation, so it does not qualify as a linear equation in one variable.

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