alleryStart learning →Substitution is easiest when one of the two rules has a particular feature. What is that feature?
ABoth unknowns appear on the same side of it
BOne unknown has a coefficient of 1 in it
CThe number on its own is larger than ten
DBoth of its coefficients are even numbers
Answer & Solution
Correct answer: B. One unknown has a coefficient of 1 in it
1. The first step of substitution is rearranging a rule to give one unknown on its own.
2. If that unknown already has a coefficient of 1, the rearranging needs no division at all.
3. With any other coefficient, dividing through brings in fractions that make the rest of the working messier.
4. So a coefficient of 1 is the feature to look for, option B.
5. Even coefficients help with the addition method rather than with substitution, so option D misplaces the advantage.
_Source: OpenStax College Algebra (CC BY 4.0), Ch 7 "Systems of Equations and Inequalities", section 7.1 Systems of Linear Equations: Two Variables_
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