10

Set 13: Systems of Equations

Explanation

Answer: C

What is the intersection point of the lines y=2x+1y = 2x + 1 and y=x+7y = -x + 7?

A.

(1,3)(1, 3)

B.

(3,7)(3, 7)

C.

(2,5)(2, 5)

✓ Correct
D.

(4,3)(4, 3)

Detailed Explanation

Choice C is correct. Choice C is the correct answer. To find the intersection, we set the two expressions for yy equal to each other. Step 1: Set the equations equal: 2x+1=x+72x + 1 = -x + 7 Step 2: Solve for xx: $$$2x + x = 7 - 13x = 6$x = 2 Step 3: Find yy using either equation (using the first): y=2(2)+1=4+1=5y = 2(2) + 1 = 4 + 1 = 5 Solution: (2,5)(2, 5) Verification: 5=2+7=55= -2 + 7 = 5 ✓ Strategic Tip: The intersection point of two lines is where their yy-values are equal for the same xx-value. Choice A is incorrect because 32(1)+1=33\neq 2(1) + 1 = 3 ✓, but 31+7=63\neq -1 + 7 = 6. Choice B is incorrect because 7=2(3)+1=77= 2(3) + 1 = 7 ✓, but 73+7=47\neq -3 + 7 = 4. Choice D is incorrect because 32(4)+1=93\neq 2(4) + 1 = 9.

Key Steps:

The correct answer is (2,5)(2, 5)

Why others are wrong:
A: Choice A is incorrect and may result from a calculation error.
B: Choice B is incorrect and may result from a calculation error.
D: Choice D is incorrect and may result from a calculation error.

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