Q. Find the numerical value of the log expression.loga=−6logb=10logc=7loga5c7bAnswer:
Apply Logarithm Rules: We are given the values of loga, logb, and logc, and we need to find the value of log(a5c7b). First, let's apply the logarithm rules to simplify the expression. Using the quotient rule of logarithms, which states that log(yx)=log(x)−log(y), we can write: log(a5c7b)=log(b)−log(a5c7)
Simplify log(b): Now let's simplify log(b). The square root can be expressed as a power of 21, so log(b)=log(b21). Using the power rule of logarithms, which states that log(xy)=y⋅log(x), we get: log(b21)=(21)⋅log(b) Since we know logb=10, we can substitute this value in: (\frac{\(1\)}{\(2\)})\cdot\log(b) = (\frac{\(1\)}{\(2\)})\cdot\(10 = 5
Simplify log(a5c7): Next, we need to simplify log(a5c7). Using the product rule of logarithms, which states that log(xy)=log(x)+log(y), we can write: log(a5c7)=log(a5)+log(c7) Now we apply the power rule to both terms: log(a5)+log(c7)=5⋅log(a)+7⋅log(c) Substituting the given values for loga and logc: 5⋅log(a)+7⋅log(c)=5⋅(−6)+7⋅7=−30+49=19
Perform Subtraction: Now we have the values for both parts of our original expression:log(a5c7b)=log(b)−log(a5c7)=5−19We can now perform the subtraction:5−19=−14
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