Solve: Fraction Division with Negative 5 Cubed in Denominator (10/(-5)³)

Question

10(5)3=? \frac{10}{(-5)^3}=\text{?}

Video Solution

Solution Steps

00:00 Simply
00:05 When there's a power on a product of elements, all of them are raised to that power
00:13 We'll use this formula in our exercise
00:20 Let's factor -5 into -1 and 5
00:28 Take out the minus
00:33 1 divided by number (A) to the power (N)
00:37 Equals the same base with the same exponent but negative
00:42 We'll use this formula in our exercise
00:51 Let's factor 10 into 2 and 5
00:56 When multiplying powers with equal bases
01:02 The power of the result equals the sum of the powers
01:04 We'll use this formula in our exercise
01:08 Let's multiply the powers
01:14 And this is the solution to the question

Step-by-Step Solution

First, let's note that:

a.

10=52 10=5\cdot2

For this, we'll recall the law of exponents for multiplication in parentheses:

(ab)n=anbn (a\cdot b)^n=a^n\cdot b^n

According to this, we get that:

(5)3=(15)3=(1)353=153=53 (-5)^3=(-1\cdot5)^3=(-1)^3\cdot5^3=-1\cdot5^3=-5^3

We want to use the understanding in 'a' to get terms with identical bases in the numerator and denominator,

Let's return to the problem and apply the understandings from 'a' and 'b':

10(5)3=2553=21553=2553 \frac{10}{(-5)^3}=\frac{2\cdot5}{-5^3}=\frac{2}{-1}\cdot\frac{5}{5^3}=-2\cdot\frac{5}{5^3}

Where in the first stage we used 'a' in the numerator and 'b' in the fraction's denominator, in the next stage we presented the fraction as a multiplication of fractions according to the rule for multiplying fractions, then we simplified the first fraction in the multiplication.

Now we'll use the law of exponents for division between terms with identical bases:

aman=amn \frac{a^m}{a^n}=a^{m-n}

Let's apply this law to the expression we got:

2553=2513=252 -2\cdot\frac{5}{5^3}=-2\cdot5^{1-3}=-2\cdot5^{-2}

where in the first stage we applied this law to the fraction in the multiplication and then simplified the expression we got,

Let's summarize the solution steps:

10(5)3=2553=252 \frac{10}{(-5)^3} =-2\cdot\frac{5}{5^3} =-2\cdot5^{-2}

Therefore, the correct answer is answer b.

Answer

2(5)2 -2(-5)^{-2}