alleryStart learning →Solve by substitution: 3x + y = 5 and 2x + 4y = -10.
A(3, -4)
B(-4, 3)
C(3, 4)
D(-3, -4)
Answer & Solution
Correct answer: A. (3, -4)
1. Solve the first equation for y: y equals 5 minus 3x.
2. Substitute into the second equation: 2x plus 4(5 minus 3x) equals -10.
3. Distribute and simplify: 2x plus 20 minus 12x equals -10, so -10x equals -30, giving x equals 3.
4. Substitute x = 3 into 3x + y = 5 to get y equals -4, giving the ordered pair (3, -4).
_Source: OpenStax Elementary Algebra (CC BY 4.0), Ch 5 "Systems of Linear Equations", section 5.2 Solve Systems of Equations by Substitution_
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