Math, asked by 05shoponline, 10 months ago

5∧-p=4∧-q=20∧r show that 1/p+1/q+1/r=0

Answers

Answered by rishu6845
6

Answer:

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Answered by Sharad001
71

Question :-

 \sf \: \:  if \: {5}^{ - p}  =  {4}^{ - q}  =  {20}^{r} \:  \\  \sf \: prove \: that \:  \frac{1}{p}  +  \frac{1}{q}  +  \frac{1}{r}  = 0

Proof :-

We have ,

 \rightarrow \sf \: {5}^{ - p}  =  {4}^{ - q}  = 20r \:   = c(say)\\  \\  if \\  \implies \sf  {5}^{ - p}  = c \\  \sf taking \:  \log \:on \: both \: sides\\  \implies \sf - p \log5 =  \log c \\  \\  \implies \sf \log5 =  -  \frac{1}{p}  \log c \:  \:  \: .....eq.(1) \\ if \:  \\  \implies \sf  {4}^{ - q}  = c \\ \sf taking  \: \log \: on \: both \: sides \\  \\  \implies \sf   \log4 =  \frac{ - 1}{q}  \log c \:  \:  \:  \: ....eq.(2) \\  \\

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now we have ,

 \rightarrow \sf \:  {20}^{r}  = c \\  \:  \\  \sf  \: taking  \: \log \: on \: both \: sides \\  \\  \rightarrow \sf r \log20 =  \log c \\  \\  \rightarrow \sf \log20 =  \frac{1}{r}  \log c \\  \\  \rightarrow \sf \log (5 \times 4) =  \frac{1}{r} \log c  \:  \\  \sf  \because \log \: mn =  \log m +  \log n \\  \therefore \\  \rightarrow \sf\log5 +  \log4 =  \frac{1}{r}  \log c \\  \\ \sf from \: eq.(1) \:  \: and \: eq.(2) \\  \\  \rightarrow \sf \frac{ - 1}{p}  \log c -  \frac{1}{q}  \log c =  \frac{1}{r}  \log c \\  \\  \rightarrow \sf \log c \{ -  \frac{1}{p}  -  \frac{1}{q}  \} =  \frac{1}{r} \log c  \\  \\  \rightarrow \boxed{ \sf{ \frac{1}{p}  +  \frac{1}{q} +  \frac{1}{r}   = 0}}

hence proved .

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