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trapecia [35]
2 years ago
15

How do you evaluate an algebraic expression?

Mathematics
1 answer:
vodomira [7]2 years ago
7 0

Answer:

  follow the Order of Operations

Step-by-step explanation:

An algebraic expression cannot be <em>evaluated</em> unless all of its variables have been replaced by numerical values. (It can be <em>simplified</em>, but not <em>evaluated</em> if it contains variables.)

A collection of numbers and math symbols is interpreted according to the Order of Operations. This order reflects a precedence of operations that is generally agreed or understood to be applied to algebraic expressions. Operations with the highest precedence are performed first. Operations with equal precedence are generally performed in order, left to right. (There are exceptions.) Parentheses or other grouping symbols are used to modify the order of operations as may be necessary.

__

Here is a description of the most often seen operations in an algebraic expression, in order of precedence (highest to lowest).

1. Parentheses or Brackets -- any expression enclosed in parentheses or brackets is evaluated first. Evaluation is according to the order of operations. That means that if parentheses are nested, expressions in the innermost parentheses are evaluated first.

2. Exponents or Indices -- Expressions with exponents are evaluated next. In this context, roots are fractional exponents. If exponents are nested, they are applied right to left:

  3^2^4 = 3^(2^4) = 3^16 = 43,046,721 . . . for example

Parentheses modify this order, so ...

  (3^2)^4 = 9^4 = 6,561

The exponent is taken to be the first number immediately following the exponentiation symbol, so ...

  9^1/2 = (9^1)/2 = 9/2 = 4.5

Again, parentheses alter this order, so ...

  9^(1/2) = √9 = 3

3. Multiplication and Division -- These operations have the same precedence, so are performed in order of appearance, left to right. Of course, division is the same as multiplication by a reciprocal, and multiplication is a commutative and associative operation. Those features of these operations do not alter the "order of operations," but may alter your approach to actually doing an evaluation.

For example, 9*2/3 would be evaluated as (9*2)/3 = 18/3 = 6. However, recognizing that 9 = 3*3, you can rearrange the evaluation to ...

  9/3*2 = 3*2 = 6

This rearrangement is allowed by the properties of multiplication, not by the Order of Operations.

You will also note that 9/3*2 is not the same as 9/(3*2). That is, the denominator in the division is only the first number after the division symbol. This is also true for expressions involving variables:

  b/2a = (b/2)*a

If you want b/(2a), you must use parentheses.

Some authors make a distinction between the slash (/) and the symbol ÷ in their effect on an expression. The Order of Operations makes no such distinction, treating /, ÷, "over", "divided by" as all meaning exactly the same thing.

4. Addition and Subtraction -- These operations have the same precedence, so are performed in order of appearance, left to right. Of course, subtraction is the same as addition of an opposite, and addition is a commutative and associative operation. Those features of these operations do not alter the "order of operations," but may alter your approach to actually doing an evaluation.

__

Based on the first letters of these operations, several mnemonic "words" or phrases have been invented to help you remember the order. Some are ...

  PEMDAS

  Please Excuse My Dear Aunt Sally

  BIDMAS

__

There are a number of tricky expressions floating around that test your understanding of the order of operations. Here is one of them:

  10 × 4 - 2 × (4² ÷ 4) ÷ 2 ÷ 1/2 + 9

One of the things that makes this tricky is the distinction between ÷ and /, as discussed above. Here, the author of the expression intends for the / to indicate a fraction, so 2÷1/2 is intended to mean 2÷(1/2).

Working this according to the order of operations, we have ...

  = 10 × 4 - 2 × (16 ÷ 4) ÷ 2 ÷ (1/2) + 9 . . . . . exponent inside parentheses

  = 10 × 4 - 2 × 4 ÷ 2 ÷ (1/2) + 9 . . . . . division inside parentheses

  = 40 - 2 × 4 ÷ 2 ÷ (1/2) + 9 . . . . . . first multiplication

  = 40 - 8 ÷ 2 ÷ (1/2) + 9 . . . . . . second multiplication

  = 40 - 4 ÷ (1/2) + 9 . . . . .  first division

  = 40 - 8 + 9 . . . . . . second division

  = 32 . . . . . . first addition

  = 41 . . . . . .  second addition

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Is the "x" a multiplication sign?
3 0
3 years ago
Did I do the first question right? can anyone please help me with the 2nd question? Would really appreciate the Help​
IgorC [24]

Answer:

  8.  1483.33

  9.  21 months

Step-by-step explanation:

8. Morgan's income after taxes is 55000/12 = 4583.33 per month. The amount  available after expenses is 4583.33 -3100.00 = 1483.33 per month.

Morgan is able to put $1483.33 per month into savings.

__

9. If Morgan is able to save $1483.33 per month, it will take her ...

  $30,000/$1483.33 ≈ 20.2

months to save $30,000. After 20 months, she won't have quite enough, so it will take her one more month to save the desired amount.

It will take Morgan about 21 months to save $30,000.

_

If you like, you can write an equation for "m", the number of months it will take Morgan to save 30,000:

  1483.33×m = 30,000

  m = 30,000/1483.33 ≈ 20.2 . . . . . . divide by the coefficient of m

7 0
3 years ago
PLZZZZ help as soon as possible
sammy [17]

Answer:

JK = 11

Step-by-step explanation:

JK ≅ JM

where

JK = 3x - 16

JM = 2x - 7

3x - 16 = 2x - 7

group like terms

3x - 2x = 16 - 7

x = 9

<u>plugin x=9 into JK</u>

JK = 3x - 16

JK = 3(9) - 16

JK = 11

6 0
3 years ago
Read 2 more answers
Find the coordinates of P ' if D o, 2.4 (x,y) is applied to the triangle below
guajiro [1.7K]

Answer:

The coordinates of P' are (4.8,-4.8).

Step-by-step explanation:

The rule of dilation D_{o,2.4}(x,y) represent the dilation with scale factor 2.4 and center at origin.

If the scale factor of the dilation is k and the center is (0,0), then

(x,y)\rightarrow (kx,ky)

Since the scale factor is 2.4, therefore

(x,y)\rightarrow (2.4x,2.4y)

From the given figure it is noticed that the coordinates of P are (2,-2). The coordinates of P' are

P(2,-2)\rightarrow P'(2.4(2),2.4(-2))

P(2,-2)\rightarrow P'(4.8,-4.8)

Therefore the coordinates of P' are (4.8,-4.8).

3 0
3 years ago
A DVD player is regularly priced at 79.95 and is on sale for 30% off. What is the discount?
evablogger [386]

Answer:

$2.40 or $77.55

Step-by-step explanation:

I don't know if you are asking for how much off or what, so I'm doing both

First, we have to find how much we have to take off or what is 30% of 79.95 so our equation is:

79.95 x 0.03 = 2.40

So 30% of 79.95 is $2.40

To find how much our new price sale is, we have to take that $2.40 off so our equation is:

79.95 - 2.4 = 77.55

So our discount price is $77.55

hope this helps:)

7 0
2 years ago
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