If (g(t)=b-7t) and the sum of (g(4), g(8), g(12)) is (258), what is (b)?
Answer and explanation
Correct answer: 142
Given \(g(t)=b-7t\), we get \(g(4)=b-28\), \(g(8)=b-56\), and \(g(12)=b-84\). Their sum is \(3b-(28+56+84)=3b-168\). Hence, \(3b-168=258\), so \(3b=426\) and \(b=142\). If 138 were used, the sum would be 246, not 258. Exam tip: First write the function value for each given input, then combine like terms carefully.
Frequently asked questions
What is the correct answer to this question?
142
Why is this the correct answer?
Given \(g(t)=b-7t\), we get \(g(4)=b-28\), \(g(8)=b-56\), and \(g(12)=b-84\). Their sum is \(3b-(28+56+84)=3b-168\). Hence, \(3b-168=258\), so \(3b=426\) and \(b=142\). If 138 were used, the sum would be 246, not 258. Exam tip: First write the function value for each given input, then combine like terms carefully.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Linear growth and decay.
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