If 7^x = 16y and 4^x = 49y then find the value of y-x .
2 years, 11 months ago
4rm equation (2)....y=4^x/49
substitutin y=4^x/49 in equation(1)
7^(x 2)=2^(2x 4)...(4rm law of indicies)
take log of both sides
(x 2)log7=(2x 4)log2
(x 2)0.845=(2x 4)0.3010
0.845x 1.69=0.602x 1.204
usin equation(2) 4^x=49y
since x=-2 and y=0.00138
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Awesome ! But try solving it by logic ( it's much easier )
@ayanlaja..you are in which grade / standard presently ?
@sharma....(lafin) that good.....do u knw any other educative wapsite or website other than brilliant?
I don't know ..
@sharma.....are u on facebook?
Nope..studious guys in India prefer to be away from such vices
@sharma.......logic? hmm....that good
Yea..because you can't find the exact ( perfect ..and not approximate )value of y by log ..but you can find it in one step by logic