7^x+5^y =74 & (7^x+1) - 5^x+1 , find the value of x,y..?
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abhi63715:
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let 7^x = a, and 5^y = b
now , a+b= 74
7a -5b = 218
(a+b = 74)× 7
(7a - 5b = 218)×1
now , 7a +7b = 518
7a - 5b = 218
now subtract both the eq..
so ,we get b= 25
( b= 5^y) so , 5^y= 25
5^y = 5^2
comparing both side .
y =2 ans .
7^x +25 = 74
7^x = 74-25
7^x =49
7^x = 7^2
x = 2 ans..
now , a+b= 74
7a -5b = 218
(a+b = 74)× 7
(7a - 5b = 218)×1
now , 7a +7b = 518
7a - 5b = 218
now subtract both the eq..
so ,we get b= 25
( b= 5^y) so , 5^y= 25
5^y = 5^2
comparing both side .
y =2 ans .
7^x +25 = 74
7^x = 74-25
7^x =49
7^x = 7^2
x = 2 ans..
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