If $f(x)=a x^{2}+b x+2$ and $f(1)=4, f(3)=38$, then $a-b=$

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Aicharya · Accepted Answer

$\begin{array}{l} f(1)=4 ; \quad a+b=2...(1) \ f(3)=38 ; \quad 9 a+3 b+2=38-	ext { (2) } \ 3 a+b=12 \end{array}$ Solving (1) \& (2) $\begin{array}{l} a=5, b=-3 \ a-b=8 \end{array}$

If $f(x)=a x^{2}+b x+2$ and $f(1)=4, f(3)=38$, then $a-b=$

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