Chapter 7: Problem 104
Perform each indicated operation. See Sections 1.4 and 5.4 $$ \left(9 y^{2}\right)\left(-8 y^{2}\right) $$
Short Answer
Expert verified
The result of the operation is \( -72y^4 \).
Step by step solution
01
Understand the operation
Identify the type of mathematical operation we are performing, which in this case is multiplication of two monomials: \( (9y^2) \) and \( (-8y^2) \).
02
Multiply the coefficients
The coefficients 9 and -8 multiply together to give the product: \( 9 \times -8 = -72 \).
03
Multiply the variables
When multiplying variables with the same base, we add their exponents. Here, both terms have the base \( y \) with exponents 2, so you add the exponents: \( y^{2+2} = y^4 \).
04
Combine the results
Combine the results of the coefficient multiplication and variable multiplication to form the final answer: \( -72y^4 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Multiplication of Monomials
When multiplying monomials, you are dealing with terms that consist of a number (known as a coefficient) and a variable raised to an exponent. To multiply two monomials, follow these simple steps:
- First, identify the coefficients and multiply them together.
- Next, look at the variables. If they have the same base, you'll add the exponents together.
- Finally, combine the results to form a new monomial.
Understanding Exponents
Exponents are a shorthand way to express repeated multiplication of a number or variable by itself. When we talk about exponents, we're basically asking how many times a number (or base) is multiplied by itself. In the expression \(y^2\), the \(2\) is the exponent, and it means \(y\) is multiplied by itself once: \(y \times y\).
One crucial rule when working with exponents, especially in multiplication, is that you add the exponents of like bases. For example:
One crucial rule when working with exponents, especially in multiplication, is that you add the exponents of like bases. For example:
- \(x^a \times x^b = x^{a+b}\)
- This means if you're multiplying \(y^2\) by \(y^2\), you simply add the 2 and 2 to get \(y^4\).
Coefficients in Monomials
Coefficients are the numerical parts of monomials. They represent how many times the variable part is counted. In the monomial \(9y^2\), 9 is the coefficient.
- Coefficients can be positive or negative numbers.
- As seen in the expression \((9y^2) \times (-8y^2)\), you multiply the coefficients just like regular numbers.
- In this case, \(9 \times -8 = -72\).
Variables in Algebraic Expressions
Variables are symbols used to represent unknown values in expressions and equations, most commonly denoted using letters like \(x, y, z\), etc. In the monomial \(9y^2\), \(y\) is the variable. Variables are crucial in algebra as they allow expressions to generalize mathematical formulas or patterns.
- Variables often come with exponents, detailing the power to which the variable is raised.
- They can be manipulated according to specific algebraic rules.
- In our example, both monomials share the variable \(y\). This makes it easier to simplify by applying exponent rules.