Algebraic Expression: Pattern for Term t

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In summary, the algebraic expression for the term t is a_n = (-1)^n * n * a_{n-1}, where a_n is the nth term in the sequence and a_{n-1} is the previous term. The sequence follows a pattern of multiplying the previous term by the current term number and changing the sign every other term. The first term in the sequence is -15.
  • #1
Natko
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Homework Statement



In this pattern, what is the algebraic expression for the term t?
-15, 30, 90, -360

Homework Equations



t= term number

The Attempt at a Solution



no idea
 
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  • #2
What do you multiply each term by to get the next?
 
  • #3
DivisionByZro said:
What do you multiply each term by to get the next?
That's what I want to find out. It does not necessarily have to be multiplication only.

In words it would be:
current term value = the previous term's value multiplied by the current term number, and change poles if the current term number is even; the first term value is -15.
 
  • #4
Are you saying that you have a sequence, [itex]a_1= -15[/itex], [itex]a_2= 30[/itex], [itex]a_3= 90[/itex], and [itex]a_4= -360[/itex]?

Well, I notice that 30= 2*15, 90= 3*30, and 360= 4*90. That is, [itex]a_n= n*a_{n-1}[/itex]. Also, the signs are -, +, +, -. You should be able to find a power of -1, in terms of n, that will give that.
 
  • #5
HallsofIvy said:
Are you saying that you have a sequence, [itex]a_1= -15[/itex], [itex]a_2= 30[/itex], [itex]a_3= 90[/itex], and [itex]a_4= -360[/itex]?

Well, I notice that 30= 2*15, 90= 3*30, and 360= 4*90. That is, [itex]a_n= n*a_{n-1}[/itex]. Also, the signs are -, +, +, -. You should be able to find a power of -1, in terms of n, that will give that.

So what would the algebraic expression to find the nth term be?
 

1. What is an algebraic expression?

An algebraic expression is a mathematical expression that contains variables, constants, and mathematical operations such as addition, subtraction, multiplication, and division. It represents a relationship between quantities and can be evaluated by substituting values for the variables.

2. What is a term in an algebraic expression?

A term in an algebraic expression is a single part of the expression separated by a plus or minus sign. It can be a number, a variable, or a combination of both. For example, in the expression 2x + 3, 2x and 3 are both terms.

3. How do you identify the pattern for term t in an algebraic expression?

The pattern for term t in an algebraic expression is determined by the coefficient and the variable. The coefficient is the number that multiplies the variable, and the variable itself represents the unknown quantity. For example, in the expression 3t + 5, the pattern for term t is 3.

4. How can you find the value of a specific term t in an algebraic expression?

To find the value of a specific term t in an algebraic expression, you can substitute the given value for the variable and simplify the expression. For example, if t = 2 in the expression 3t + 5, the value of term t would be 3(2) + 5 = 11.

5. Why is understanding the pattern for term t important in algebraic expressions?

Understanding the pattern for term t in an algebraic expression allows you to identify the relationship between quantities and make predictions about their values. It also helps in solving equations and simplifying expressions by identifying common factors or terms.

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