Q. Solve this system of equations: \(y = x – 4\) and \(y = 6x – 10\).
Answer
From \(y=x-4\) and \(y=6x-10\) we have \(x-4=6x-10\). Adding 10 and subtracting x gives \(6=5x\), so \(x=\tfrac{6}{5}\). Then \(y=x-4=\tfrac{6}{5}-4=-\tfrac{14}{5}\).
Solution: \((x,y)=\bigl(\tfrac{6}{5},-\tfrac{14}{5}\bigr)\)
Detailed Explanation
Solution — step-by-step
-
We are given two expressions for y. Because both right-hand sides equal y, they are equal to each other. Set them equal:
\[ x – 4 = 6x – 10 \]
Explanation: If y = A and y = B, then A = B. This reduces the system to a single equation in x.
-
Eliminate x from one side by subtracting x from both sides:
\[ x – 4 – x = 6x – 10 – x \]
Simplify each side:
\[ -4 = 5x – 10 \]
Explanation: Subtracting the same quantity from both sides preserves equality. The left side becomes -4 because x – x = 0; the right side combines 6x – x = 5x.
-
Isolate the term with x by adding 10 to both sides:
\[ -4 + 10 = 5x – 10 + 10 \]
Simplify:
\[ 6 = 5x \]
Explanation: Adding 10 to both sides cancels the -10 on the right, leaving 5x alone on the right-hand side.
-
Divide both sides by 5 to solve for x:
\[ x = \frac{6}{5} \]
Explanation: Division by 5 isolates x because 5x divided by 5 equals x.
-
Find y by substituting x back into either original equation. Using y = x – 4:
\[ y = \frac{6}{5} – 4 \]
Write 4 as a fraction with denominator 5: 4 = \frac{20}{5}, then
\[ y = \frac{6}{5} – \frac{20}{5} = -\frac{14}{5} \]
Explanation: Substitution gives the corresponding y-value. Converting to common denominators yields the exact fraction.
-
Optional check: Use the second equation y = 6x – 10 to verify the same y:
\[ y = 6\left(\frac{6}{5}\right) – 10 = \frac{36}{5} – \frac{50}{5} = -\frac{14}{5} \]
Both equations give the same y, so the solution is consistent.
-
Final answer (ordered pair):
\[ \left(\frac{6}{5}, -\frac{14}{5}\right) \]
Graph
FAQs
How do you solve the system \(y = x - 4\) and \(y = 6x - 10\)?
How many solutions does this system have?
Are the lines parallel or perpendicular?
How can I check the solution is correct?
How would you solve this by elimination?
What are the slopes and y-intercepts of the lines?
How would I sketch the graph quickly?
What if the equations were identical or gave a contradiction?
Math, Calculus, Geometry, etc.