Question

Solve the system y = x + 5 and y = 2x - 7

Original question: 2. y = x + 5 y = 2x - 7

(12, 17) y = 2x - 7 1x + 5 = 2x - 7 -1x + 5 = -7 -1x = -12 x = 12 y = 17

Expert Verified Solution

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Expert intro: Both equations are already written as expressions for yy, so set them equal to each other. That gives a direct path to the intersection point.

Detailed walkthrough

We solve

y=x+5y=x+5

y=2x7.y=2x-7.

Since both equal yy, set the right-hand sides equal:

x+5=2x7.x+5=2x-7.

Subtract xx from both sides:

5=x7.5=x-7.

Add 7 to both sides:

x=12.x=12.

Now substitute into either equation:

y=12+5=17.y=12+5=17.

So the solution is

(12,17).\boxed{(12,17)}.

💡 Pitfall guide

A common error is mixing up the variables and solving for yy first when both equations already give yy directly. Setting the expressions equal is the cleanest method here.

🔄 Real-world variant

If one equation were instead in terms of xx, you could still solve by substitution or elimination. The key idea is that the intersection point must satisfy both equations at the same time.

🔍 Related terms

intersection point, substitution, linear equations

FAQ

What is the solution to y = x + 5 and y = 2x - 7?

Set x + 5 = 2x - 7, solve to get x = 12, then substitute back to get y = 17. The solution is (12, 17).

Why do we set the two expressions for y equal?

Because both equations represent the same y-value at the intersection point, so their right-hand sides must be equal there.

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