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Why can 5x=−35^x=-35x=−3 have no real solution?
A
An exponential output is always positive: 5x>05^x>05x>0.
B
There is no solution.
C
The logarithmic form of ax=ba^x=bax=b is x=logab\boxed{x=\log_a b}x=logab.
D
Taking natural logarithms of 32x−1=73^{2x-1}=732x−1=7 gives (2x−1)ln3=ln7\boxed{(2x-1)\ln3=\ln7}(2x−1)ln3=ln7.
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1.6.7 Equations involving exponentials Flashcards
22 flashcards on OCR A Level Maths 1.6.7 Equations involving exponentials: the key formulae, methods and definitions you need to recall for Paper 1, Paper 2 and Paper 3.