Interpret coefficients, constants, terms, factors, and solutions. | Linear equations in one variable | SAT Math

Coefficients represent rates, constants represent fixed values, and the solution tells you what the equation means in context.

核心知识

Every part of an equation has meaning: coefficients show rate of change, constants show fixed values, and the solution tells you when or where a condition is met.

深入理解

The SAT doesn't just ask you to solve — it asks what the pieces of an equation mean. In $𝐶 = 15 𝑡 + 40$ , the coefficient 15 is the cost per hour, and the constant 40 is the flat fee charged regardless of time.

A coefficient multiplies the variable and usually represents a rate, price per unit, or slope. A constant is a fixed number that doesn't change with the variable — think starting amounts, flat fees, or initial values.

Terms are the individual parts separated by $+$ or $-$ signs. Factors are quantities that are multiplied together within a term. The solution is the value that makes the equation true, and in context it answers a question like "how many hours" or "what price."

When interpreting, always connect back to the scenario described in the problem. The math label (coefficient, constant) tells you the structural role; the word problem tells you the real-world meaning.

常见误解

Confusing coefficients with constants — thinking the number in front of the variable is a fixed amount rather than a per-unit rate.
Interpreting the solution of the equation without considering the context — saying $𝑥 = 3$ without stating what 3 represents.
Mixing up terms and factors: in $5 𝑥$ , the term is $5 𝑥$ , while 5 and $𝑥$ are its factors.

题目

示例解析

A plumber charges a flat fee of $75 plus $50 per hour. The total cost $𝐶$ , in dollars, for $ℎ$ hours of work is given by $𝐶 = 50 ℎ + 75$ . What does the number 50 represent in this equation?

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