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MHT CET · Maths · Functions

If \(\mathrm{f}(\mathrm{x})=2\{\mathrm{x}\}+5 \mathrm{x}\), where \(\{\mathrm{x}\}\) is fractional part function, then \(f(-1.4)\) is

  1. A 8.2
  2. B -8.2
  3. C -5.8
  4. D -5
Verified Solution

Answer & Solution

Correct Answer

(C) -5.8

Step-by-step Solution

Detailed explanation

We know that \(\mathrm{x}=[\mathrm{x}]+\{\mathrm{x}\}\)
When \(\mathrm{x}=-1.4\), we get \([\mathrm{x}]=-2\) and \(\{\mathrm{x}\}=0.6\)
We have \(f(x)=2\{x\}+5 x\)
\(\therefore \mathrm{f}(-1.4)=2(0.6)+5(-1.4)=-7+1.2=-5.8\)