Question

Evaluate the expressions without using a calculator. $$ -5^{3} \cdot-2^{2} $$

Short answer

Question: Evaluate the expression \(-5^3 \cdot -2^2\) without using a calculator. Answer: 500

Step-by-step solution

Evaluate the exponents

We have two exponents to calculate, one for \(-5^3\) and another for \(-2^2\). For \(-5^3\), we have: $$ (-5)^3 = (-5) \cdot (-5) \cdot (-5) $$ For \(-2^2\), we have: $$ (-2)^2 = (-2) \cdot (-2) $$

Calculate the products

Now that we have the bases and exponents calculated, we will compute the products of the expression. For \((-5)^3\), calculate: $$ (-5) \cdot (-5) \cdot (-5) = 125 $$ For \((-2)^2\), calculate: $$ (-2) \cdot (-2) = 4 $$

Multiply the results

Lastly, we need to multiply the results from step two to get the final answer: $$ 125 \cdot 4 = 500 $$ So the evaluation of the given expression is 500.

Key concepts

Negative Numbers

Negative numbers can be tricky, but they follow specific rules that make calculations straightforward when you understand them. A negative number is any number less than zero, represented with a minus sign (-). When dealing with negative numbers, it's important to remember how they interact during multiplication and exponentiation.

• Multiplying two negative numbers results in a positive number. For example, \((-2) \times (-2) = 4\).
• Multiplying a negative number by a positive number results in a negative number. For example, \((-5) \times 2 = -10\).

It's crucial to be mindful of the order and number of negative numbers involved to determine the correct sign of the result. When dealing with exponents, consider whether the entire base is negative and raised to the power (in parentheses), or if just the base number is raised and then negated. The calculated results can differ based on this placement, so always pay attention to parentheses, especially with negative bases.

Order of Operations in Algebra

Solving algebraic expressions in the correct sequence is essential for accurate calculations. This sequence is determined by the order of operations, often remembered using the acronym PEMDAS:

• Parentheses
• Exponents
• Multiplication and Division (from left to right)
• Addition and Subtraction (from left to right)

In the given expression, \((-5)^3 \cdot\ (-2)^2\), the use of exponents is addressed first. We calculate the powers before proceeding to any multiplication.
Remember to apply each step in sequence and pay attention to not only the operations but also the values on either side of those operations. Proper attention to the order helps avoid miscalculations and ensures your final results are correct.

Multiplication Techniques

In algebra, multiplication often involves complex numbers and signs, but using proven techniques can simplify calculations. One efficient way is breaking down the problem like in the example:

• Compute the powers first, which are forms of repeated multiplication.
• For example, \((-5)^3 = (-5) \times (-5) \times (-5)\).
• Resulting in 125, a positive number due to the even number of negative signs.
• Then multiply that by the result of the second power, \((-2)^2 = 4\), leading to \((125 \times 4) = 500\).

This systematic breakdown makes multiplying large or complex numbers more manageable. Remember to consider the sequence and signs at each stage. Double-check your work to ensure the signs and numbers are accurate. These techniques bring clarity to potentially complicated expressions and make solving them less intimidating.