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Ch. 1 - Equations and Inequalities
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
2장, 문제 7

Solve each problem. If x represents the number of pennies in a jar in an applied problem, which of the following equations cannot be a correct equation for finding x? (Hint:Solve the equations and consider the solutions.)
A. 5x+3 =11
B.12x+6 =-4
C.100x =50(x+3)
D. 6(x+4) =x+24

검증된 단계별 안내
1
Step 1: Understand the context of the problem. Since \( x \) represents the number of pennies in a jar, \( x \) must be a non-negative integer (\( x \geq 0 \)) because you cannot have a negative number of pennies.
Step 2: Solve each equation for \( x \) to find its solution.
For equation A: \( 5x + 3 = 11 \), subtract 3 from both sides to get \( 5x = 8 \), then divide both sides by 5 to find \( x = \frac{8}{5} \).
For equation B: \( 12x + 6 = -4 \), subtract 6 from both sides to get \( 12x = -10 \), then divide both sides by 12 to find \( x = -\frac{10}{12} = -\frac{5}{6} \).
For equation C: \( 100x = 50(x + 3) \), expand the right side to get \( 100x = 50x + 150 \), subtract \( 50x \) from both sides to get \( 50x = 150 \), then divide both sides by 50 to find \( x = 3 \).
For equation D: \( 6(x + 4) = x + 24 \), expand the left side to get \( 6x + 24 = x + 24 \), subtract \( x \) and 24 from both sides to get \( 5x = 0 \), then divide both sides by 5 to find \( x = 0 \).
Step 3: Analyze the solutions in the context of the problem. Since \( x \) must be non-negative, any negative solution is not valid for the number of pennies.
Step 4: Identify which equation(s) yield invalid solutions. Equation B gives \( x = -\frac{5}{6} \), which is negative and therefore cannot represent the number of pennies.
Step 5: Conclude that equation B cannot be a correct equation for finding \( x \) in this applied problem.

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