4
algebra

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)

D

(4,3)(4, 3)

Correct Answer: C

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=712x + x = 7 - 13x=63x = 6x=2x = 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 because3 eq2(1)+1=33 \ eq 2(1) + 1 = 3 ✓, but 3 eq1+7=63 \ eq -1 + 7 = 6.

Choice B is incorrect because7=2(3)+1=77 = 2(3) + 1 = 7 ✓, but 7 eq3+7=47 \ eq -3 + 7 = 4.

Choice D is incorrect because3 eq2(4)+1=93 \ eq 2(4) + 1 = 9.