Solve for x 1/x+1/4=7/12

Subtract ${\displaystyle \frac{1}{4}}$ from both sides of the equation.

To write ${\displaystyle -\frac{1}{4}}$ as a fraction with a common denominator, multiply by ${\displaystyle \frac{3}{3}}$.

Write each expression with a common denominator of ${\displaystyle 12}$, by multiplying each by an appropriate factor of ${\displaystyle 1}$.

Combine the numerators over the common denominator.

Subtract ${\displaystyle 3}$ from ${\displaystyle 7}$.

Cancel the common factor of ${\displaystyle 4}$ and ${\displaystyle 12}$.

Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.

Since ${\displaystyle x,3}$ contain both numbers and variables, there are two steps to find the LCM. Find LCM for the numeric part ${\displaystyle 1,3}$ then find LCM for the variable part ${\displaystyle x^1}$.

The LCM is the smallest positive number that all of the numbers divide into evenly.

The number ${\displaystyle 1}$ is not a prime number because it only has one positive factor, which is itself.

Since ${\displaystyle 3}$ has no factors besides ${\displaystyle 1}$ and ${\displaystyle 3}$.

The LCM of ${\displaystyle 1,3}$ is the result of multiplying all prime factors the greatest number of times they occur in either number.

The factor for ${\displaystyle x^1}$ is ${\displaystyle x}$ itself.

The LCM of ${\displaystyle x^1}$ is the result of multiplying all prime factors the greatest number of times they occur in either term.

The LCM for ${\displaystyle x,3}$ is the numeric part ${\displaystyle 3}$ multiplied by the variable part.

Multiply each term in ${\displaystyle \frac{1}{x}=\frac{1}{3}}$ by ${\displaystyle 3x}$.

Simplify the left side.

Simplify the right side.