Tag Archive: negative sign

E-Math Note : Usage of bracket in Expansion

Written on November 20, 2007 by Ai Ling in E-Maths, Learning Tools
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Another TIP for students taking Elementary Mathematics (E-Math)

Qn: Expand and Simplify the following:

(y+z)^2-(y-z)^2

Method 1 : Expansion using one of the Algebraic rules

(y+z)^2-(y-z)^2 =y^2+2yz+z^2-y^2-2yz+z^2

Did you see what is not right?

Method 2: Recognizing (A)^2 – (B)^2=(A+B)(A-B)

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

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