Question 24·200 Super-Hard SAT Math Questions·Algebra
One of the two equations in a system of linear equations is given. The system has no solution. Which choice could be the second equation in this system?
First simplify the given equation: move any variable terms to one side, then clear denominators to get integer coefficients. For no solution, look for a second equation whose - and -coefficients are a constant multiple of the first equation’s coefficients, but whose constant term is not multiplied by that same constant.
Hints
Get all variable terms on one side
Move the term to the left so the right side is just a constant.
Clear the fractions efficiently
After combining the -terms, multiply the entire equation by the least common multiple of , , and .
Use proportionality
For no solution, the - and -coefficients must be in the same ratio between the two equations, but the constants must not be in that ratio.
Desmos Guide
Graph the given equation
Enter 4/5 x - 6/7 y = 8/35 + 1/10 x in Desmos.
Graph each answer choice
Enter each option as a second equation (one at a time).
Identify the no-solution case
Choose the option whose graph is a different line that never intersects the first line (parallel lines with different intercepts).
Step-by-step Explanation
Rewrite the given equation in standard form
Start with
Move the -term on the right to the left:
Compute the coefficient:
so
Multiply both sides by :
Use the no-solution condition
Two linear equations have no solution when they are parallel but not the same line.
In standard form, that means the - and -coefficients are proportional, but the constant term is not proportional by the same factor.
Scan for a proportional left side but mismatched constant
We want an answer choice where the left side is for some constant , but the right side is not .
Check the matching choice
For , the left side is
If it were the same line as , the constant would be , but the choice has .
So the lines are parallel and distinct, giving no solution. Therefore, the second equation could be .