Mathematics: Which are useful ways of finding the value of a variable

Which are useful ways of finding the value of

LaToyaShante1228

09.10.2020

d. −7/32

Step-by-step explanation:

The expression that we have to evaluate in this problem is:

$7x^{-3}y^{-1}$

We have to evaluate this expression for:

x = -2

y = 4

We start by rewriting the expression by rewriting it using the following:

$a^{-n}=\frac{1}{a^n}$

So the expression can be rewritten as

$7x^{-3}y^{-1}=\frac{7}{x^3 y}$

Now we observe that:

(-2)^3=(-2)(-2)(-2)=-8

Therefore, by substituting x = -2 and y = 4 into the expression, we find:

$\frac{7}{(-2)^3\cdot 4}=\frac{7}{-8\cdot 4}=-\frac{7}{32}$

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