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Lesechka [4]
2 years ago
10

If log(x + y) = log 3 + ½log x + ½log y, prove that x² + y² = 7xy​

Mathematics
2 answers:
Free_Kalibri [48]2 years ago
7 0

Answer:

See Explanation

Step-by-step explanation:

log(x + y) = log3 +  \frac{1}{2} logx+  \frac{1}{2} logy \\  \\ log(x + y) = log3 +    logx ^{\frac{1}{2}} +   logy ^{\frac{1}{2}}\\  \\  log(x + y) = log3 +    log(xy) ^{\frac{1}{2}} \\  \\ log(x + y) =  log[3(xy) ^{\frac{1}{2}}] \\  \\ x + y = 3(xy) ^{\frac{1}{2}} \\  \\ squaring \: both \: sides \\  {(x + y)}^{2}  =  \bigg(3(xy) ^{\frac{1}{2}} \bigg)^{2}  \\  \\  {x}^{2}  +  {y}^{2}  + 2xy = 9xy \\  \\  {x}^{2}  +  {y}^{2}  = 9xy - 2xy \\  \\   \purple{ \bold{{x}^{2}  +  {y}^{2}  = 7xy}} \\ thus \: proved

snow_tiger [21]2 years ago
7 0

Answer:

\boldsymbol {Rule} : \\\\  \boldsymbol {\log _ n a+\log _n b = \log _n a\cdot b} \\\\ \boldsymbol {n \cdot \log _a b =\log_a b ^n   } \\\\ \large \boldsymbol {} \log _n (x+y)= \log_n  3 + \frac{1}{2}  \log_n  x+\frac{1}{2} \log _n y   \\\\ \log _n (x+y) = \log _n 3+\frac{1}{2} (\log_n  xy  )  \\\\ \log _n ( x+y ) = \log_n  3+\log _n \sqrt{xy }  \\\\ \log _n (x+y) = \log_n   \ 3  \sqrt{xy }  \\\\ x+y= 3\sqrt{xy} \\\\ (x+y) ^2= (3\sqrt{xy} })^2 \\\\ x^2+y^2+2xy =9 xy  \\\\ \boldsymbol {x^2+y^2=7xy }

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