10

Set 16: Systems of Equations (Advanced)

Explanation

Answer: B

Solve using your preferred method: {3x+2y=18x4y=8\begin{cases} 3x + 2y = 18 \\ x - 4y = -8 \end{cases}

A.

(3,4.5)(3, 4.5)

B.

(4,3)(4, 3)

✓ Correct
C.

(2,6)(2, 6)

D.

(5,1.5)(5, 1.5)

Detailed Explanation

Choice B is correct. Choice B is the correct answer. I'll use substitution. From second equation: x=4y8x = 4 y - 8. Step 1: Substitute into first equation: 3(4 y - 8) + 2 y = 18$12y - 24 + 2 y = 1814y = 42y = 3$$ Step 2: Find x: $$x = 4(3) - 8 = 12 - 8 = 4$$ Solution: (4, 3)Verification:Verification:3(4) + 2(3) = 18✓ and $$4- 4(3) = -8$$ ✓ Strategic Tip: With coefficient 1 on x in second equation, substitution is efficient. Choice A is incorrect because3(3) + 2(4.5) = 18✓, but $$3- 4(4.5) = -15 \neq -8$$. Choice C is incorrect because3(2) + 2(6) = 18✓, but $$2- 4(6) = -22 \neq -8$$. Choice D is incorrect because3(5) + 2(1.5) = 18$ ✓, but 54(1.5)=185- 4(1.5) = -1 \neq -8.

Key Steps:

The correct answer is (4,3)(4, 3)

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