MHT CET · Maths · Quadratic Equation
If \(f(x)=a x^{2}+b x+2\) and \(f(1)=4, f(3)=38\), then \(a-b=\)
- A 15
- B -2
- C 2
- D 8
Answer & Solution
Correct Answer
(D) 8
Step-by-step Solution
Detailed explanation
\(
\begin{array}{l}
f(1)=4 ; \quad a+b=2...(1) \\
f(3)=38 ; \quad 9 a+3 b+2=38-\text { (2) } \\
3 a+b=12
\end{array}
\)
Solving (1) \& (2)
\(
\begin{array}{l}
a=5, b=-3 \\
a-b=8
\end{array}
\)
\begin{array}{l}
f(1)=4 ; \quad a+b=2...(1) \\
f(3)=38 ; \quad 9 a+3 b+2=38-\text { (2) } \\
3 a+b=12
\end{array}
\)
Solving (1) \& (2)
\(
\begin{array}{l}
a=5, b=-3 \\
a-b=8
\end{array}
\)
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