If fx - 2x-5x2 - x - 5- then f - f- 1 - is equal to

The correct option is C 155149 Given expression is f(x)= 2x+5 x ^ 2 +x+5 ∴ #160;f( 1)= 2× ( 1)+5 ( 1)^ 2 +( 1)+5 = 3 5 ∴ #160;f( f( ...

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Standard XII

Mathematics

Derivative from First Principle

If fx = 2x+...

Question

If $f (x) = \frac{2 x + 5}{x^{2} + x + 5}$ , then $f [f (- 1)]$ is equal to

\frac{149}{155}

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\frac{155}{147}

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\frac{155}{149}

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\frac{147}{155}

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Solution

The correct option is C $\frac{155}{149}$
Given expression is $f (x) = \frac{2 x + 5}{x^{2} + x + 5}$
$∴ f (- 1) = \frac{2 \times (- 1) + 5}{(- 1)^{2} + (- 1) + 5} = \frac{3}{5}$
$∴ f (f (- 1)) = \frac{2 \times \frac{3}{5} + 5}{{(\frac{3}{5})}^{2} + \frac{3}{5} + 5} = \frac{155}{149}$

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Similar questions

The heights (in cm) of 9 students of a class are
148, 144, 152, 155, 160, 147, 150, 149, 145.
Find the median height.

The heights (in cm) of 30 students of class VIII are given below:

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Prepare a frequency distribution table with 160-164 as one of the class intervals.

${(\frac{- 1}{5})}^{3} \div {(\frac{- 1}{5})}^{8}$ is equal to
(a) ${(\frac{- 1}{5})}^{5}$
(b) ${(\frac{- 1}{5})}^{11}$
(c) $(- 5)^{5}$
(d) ${(\frac{1}{5})}^{5}$

Q. Simplify:

\frac{155 \times 155 \times 155 - 55 \times 55 \times 55}{155 \times 155 + 155 \times 55 + 55 \times 55}

Q. Evaluate:

∣ ∣ ∣ ∣ ∣ \begin{matrix} \sqrt{23} + \sqrt{3} & \sqrt{5} & \sqrt{5} \sqrt{46} + \sqrt{15} & 5 & \sqrt{10} \sqrt{115} + 3 & \sqrt{15} & 5 \end{matrix} ∣ ∣ ∣ ∣ ∣

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If f(x)=2x+5x2+x+5, then f[f(−1)] is equal to

The correct option is C 155149Given expression is f(x)=2x+5x2+x+5∴f(−1)=2×(−1)+5(−1)2+(−1)+5=35∴f(f(−1))=2×35+5(35)2+35+5=155149

If $f (x) = \frac{2 x + 5}{x^{2} + x + 5}$ , then $f [f (- 1)]$ is equal to

The correct option is C $\frac{155}{149}$
Given expression is $f (x) = \frac{2 x + 5}{x^{2} + x + 5}$
$∴ f (- 1) = \frac{2 \times (- 1) + 5}{(- 1)^{2} + (- 1) + 5} = \frac{3}{5}$
$∴ f (f (- 1)) = \frac{2 \times \frac{3}{5} + 5}{{(\frac{3}{5})}^{2} + \frac{3}{5} + 5} = \frac{155}{149}$