ICSE Class 10 Answered

Q. 22

Asked by Rayeesa | 10 Apr, 2018, 07:26: AM

Expert Answer

begin mathsize 14px style 7 to the power of straight x plus 1 end exponent plus 7 to the power of 1 minus straight x end exponent equals 50 rightwards double arrow 7 to the power of straight x.7 plus 7.7 to the power of negative straight x end exponent equals 50 Let space 7 to the power of straight x equals straight y rightwards double arrow 7 straight y plus 7 over straight y equals 50 rightwards double arrow 7 straight y squared minus 50 straight y plus 7 equals 0 rightwards double arrow 7 straight y squared minus 49 straight y minus straight y plus 7 equals 0 rightwards double arrow 7 straight y left parenthesis straight y minus 7 right parenthesis minus 1 left parenthesis straight y minus 7 right parenthesis equals 0 rightwards double arrow left parenthesis straight y minus 7 right parenthesis left parenthesis 7 straight y minus 1 right parenthesis equals 0 rightwards double arrow straight y equals 7 space or space straight y equals 1 over 7 rightwards double arrow 7 to the power of straight x equals 7 space or space 7 to the power of straight x equals 1 over 7 rightwards double arrow straight x equals 1 space or space straight x equals negative 1 end style

Answered by Rashmi Khot | 10 Apr, 2018, 09:18: AM

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