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5 votes
Given


log(x) = 2 \: and \: log(y) = - 1
prove that

xy - 100y {}^(2) = 9



1 Answer

4 votes

Explanation:


log(x) = 2 \\ {10}^(2) = x \\ x = 100

then for y:


log( y) = - 1 \\ {10}^( - 1) = y \\ y = 0.1

so:


xy - 100 {y}^(2) \\ = 100 * 0.1 - 100 * {(0.1)}^(2) \\ = 10 - 100 * 0.01 \\ = 10 - 1 \\ = 9

User Balaji Dhanasekar
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