Another TIP for students taking Elementary Mathematics (E-Math)

Qn: Expand and Simplify the following:

[tex](y+z)^2-(y-z)^2[/tex]

Method 1 : Expansion using one of the Algebraic rules

[tex](y+z)^2-(y-z)^2

=y^2+2yz+z^2-y^2-2yz+z^2[/tex]

Did you see what is not right?

Method 2: Recognizing [tex](A)^2 – (B)^2=(A+B)(A-B) [/tex]

so [tex](y+z)^2-(y-z)^2=(y+z+y-z)(y+z-[y-z])[/tex]

Method 1:

[tex](y+z)^2-(y-z)^2

=y^2+2yz+z^2-y^2-2yz+z^2[/tex]

Bracket is missing! the negative sign belongs to the expansion of [tex](y-z)^2[/tex] not just [tex]y[/tex]

Correct Ans:

[tex](y+z)^2-(y-z)^2

=y^2+2yz+z^2-(y^2-2yz+z^2)[/tex]

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common mistake, correct usage of bracket, expansion, negative sign