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Evaluate the given expression |-4b-8| + |-1-b2| + 2b3 for b = -2

  • Last Updated : 19 Jan, 2022

Algebraic Expression is made up of variables and constants along with algebraic operations such as addition, subtraction, etc.. these Expressions are made up of terms. Algebraic expressions are the equations when the operations such as addition, subtraction, multiplication, division, etc. are operated upon any variable.

A combination of terms by the operations such as addition, subtraction, multiplication, division, etc is termed as an algebraic expression (or) a variable expression.

e.g.: 2x + 4y – 7, 3x – 10, etc.

The above expressions are represented with the help of unknown variables, constants, and coefficients. The combination of these three terms is termed as an expression. Unlike the algebraic equation, it has no sides or ‘equals to’ sign.

Types of Algebraic Expression

Algebraic Expressions are of three types based on the number of terms in the expression:

  • Monomial Expression
  • Binomial Expression
  • Polynomial Expression

Monomial Expression

An expression that has only one term is termed a Monomial expression.

Examples of monomial expressions include 5x4, 3xy, 2x, 5y, etc.

Binomial Expression

An algebraic expression which is having two terms and unlike are termed as a binomial expression

Examples of binomial include 2xy + 8, xyz + x2, etc.

Polynomial Expression

An expression that has more than one term with non-negative integral exponents of a variable is termed a polynomial expression.      

Examples of polynomial expression include ax + by + ca, x3 + 5x + 3, etc.

Other Types of Expression

We have other expressions also apart from monomial, binomial, and polynomial types of expressions which are

  • Numeric Expression
  • Variable Expression

Numeric Expression

An expression that consists of only numbers and operations, but never includes any variable is termed a numeric expression.

Some of the examples of numeric expressions are 14 + 5, 18 ÷ 2, etc.

Variable Expression

An expression that contains variables along with numbers and operations to define an expression is termed as A variable expression.

Some examples of a variable expression include 4x + y, 5ab + 53, etc.

Some Important Algebraic Formulas

There are some terms of algebraic expression which basically used,

(a + b)2 = a2 + 2ab + b2

(a – b)2 = a2 – 2ab + b2

(a + b)(a – b) = a2 – b2

(x + a)(x + b) = x2 + x(a + b) + ab

(a + b)3 = a3 + b3 + 3ab(a + b)

(a – b)3 = a3 – b3 – 3ab(a – b)

a3 – b3 = (a – b)(a2 + ab + b2)

a3 + b3 = (a + b)(a2 – ab + b2)

Example: If 2x2+3xy+4x+7 is an algebraic expression. Determine the equation.

Solution:

2x2, 3xy, 4x, and 7 are the Terms

Coefficient of term: 2 is the coefficient of x2

Constant term: 7

Variables: here x, y are variables

Factors of a term: If 2xy is a term, then its factors are 2, x, and y.

Evaluate the given expression |-4b-8| + |-1-b2| + 2b3 for b = -2.

Solution: 

Given term : b = -2

= |-4b-8|+|-1-b2 |+2b3

= |-4(-2)-8|+|-1-(-2)2 |+2(-2)3

= |8 -8|+|-1- 4 |+2(-8)

= |0 |+|-5 | – 16                   {modulus always gives positive value}

= 5 – 16 

= -11

Similar Problems 

Problem 1: Add 6x2–7x+3, –8x2+2x–5 and 7x2–x–2

Solution:

Given:  6x2–7x+3, –8x2+2x–5 and 7x2 – x – 2

Now add the like terms together

= {6x2 + (-8x2) + 7x2} + {(-7x) + 2x -x} + {3 -5 -2}

= {6x2 – 8x2 + 7x2} + {-7x + 2x – x} + (-4)

= 5x2 + (-6x) – 4

= 5x2 -6x – 4

Problem 2: Simplify: 9 – 3(x – 1)

Solution:

Here we have

9 – 3(x – 1)

= 9 – 3x +3

= 12 – 3x

= -3x + 12

= -3( x – 4 ) 

Problem 3: Simplify (x2 + 18x +81)/(x2 – 64) × (x + 8)/(x + 9).

Solution:

Given that : (x2 + 18x +81)/(x2 – 64) × (x + 8)/(x + 9).

 =  (x2 + 18x +81)/(x2-64) × (x + 8)/(x + 9)

By factorizing the above terms

=  {(x+9)(x + 9) / (x2 – 82)} × {(x + 8)/(x+9)}

By using a2 – b2 = (a + b) (a – b)

= {(x+9)(x + 9) / (x – 8)(x + 8)} × {(x + 8)/ (x+9)}                  

By simplifying

=  (x + 9)(x – 8)

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