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SAI International School

                                                      CLASS-VII
               Mathematics
               CHAPTER-12: Algebraic Expression

               LESSON NOTES- 12.2


               SUBTOPIC: Addition and subtraction of algebraic expression


               Addition of algebraic expressions:

                     The simplest expressions are monomials.

                     They consist of only one term.

                     So while adding monomials we just need to add the digits and keep the
                       variable as it is.

                         Ex- Let us add 3x and 4x
                                       3x + 4x = (3 × x) + (4 × x)

                                                    = (3 + 4) × x (using distributive law)

                                                    = 7 × x or 7x
                                            or 3x + 4x = 7x

                     Except monomials in the rest case while adding we have separate the like

                       terms and unlike terms, then add the like terms by keeping the variable same
                       and the unlike terms with remain as it is.

                     Note, unlike terms cannot be added or subtracted the way like terms are
                       added or subtracted.

                     The sum of two or more like terms is a like term with a numerical coefficient

                       equal to the sum of the numerical coefficients of all the like terms.
                     The addition can be done horizontally and vertically also.

                     Ex: Add 5x + 7 and 2x + 10

                              Sum = (5x + 7) + (2x + 10)
                                      = 5x + 7 + 2x + 10

                                      = (5x + 2x) + (7 + 10)
                                       = 7x + 17
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