Question 15·Hard·Linear Equations in One Variable
If , the solution is between which pair of consecutive integers?
For equations with several fractions, first distribute to remove parentheses, then immediately clear fractions by multiplying every term on both sides by a common multiple of the denominators so you only deal with whole numbers. From there, solve the linear equation using standard moves (collect like terms, isolate the variable), and convert your final fraction to a decimal if needed to see between which two integers it falls—this is faster and less error-prone than guessing or plugging in the answer choices.
Hints
Start by expanding the parentheses
Rewrite and by distributing the fraction to both terms inside each set of parentheses.
Combine like terms carefully
After distributing, be sure to distribute the minus sign in front of , then combine all the terms together and all the constant terms together on the left side.
Get rid of the fractions
Once you have an equation with fractions, multiply every term on both sides by a common multiple of the denominators (12 works here) to turn it into an equation with whole numbers.
Solve and interpret the result
Solve the resulting simple equation for , then write your final answer as a decimal so you can see which two consecutive integers it falls between.
Desmos Guide
Enter the two sides as separate functions
In Desmos, type y = (3/4)(2x - 5) - (5/6)(x + 7) on one line and y = x/2 + 1 on another line so you have two graphs on the same coordinate plane.
Find the intersection point
Zoom and pan until you can see where the two graphs intersect. Tap or click on the intersection point and note the x-coordinate; that value of solves the equation.
Match the x-value to an answer choice
Look at the x-coordinate from Desmos and determine which pair of consecutive integers it lies between, then select the answer choice whose interval matches that pair.
Step-by-step Explanation
Distribute and simplify each side
Start by expanding the fractions:
- Left side:
So the equation becomes:
Distribute the minus sign across the parentheses:
Now combine like terms on the left:
- For terms: , so the term is .
- For constants: .
So the equation simplifies to:
Clear the fractions
To remove the fractions, multiply every term on both sides by 12 (the least common multiple of 3, 12, and 2):
Compute each term:
So the equation becomes:
Solve the linear equation for x
Now solve .
- Subtract from both sides:
which simplifies to
- Add 115 to both sides:
Now you have a simple equation with no fractions.
Find x and determine the correct interval
From , divide both sides by 2:
Convert this to a decimal to see which integers it is between:
The number lies between 63 and 64, so the solution is between 63 and 64.