evaluate through algebraic identities :
1 ) 2.8²
2 ) 31² - 29²
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evaluate through algebraic identities :
1 ) 2.8²
2 ) 31² - 29²
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Answer:
[tex]2.8^2[/tex] is 7.84 and [tex]31^2-29^2[/tex] is 120.
Step-by-step explanation:
Using the algebraic identity,
[tex](a-b)^2= a^2-2ab+b^2[/tex]
we can write [tex]2.8^2[/tex] as
[tex](3-0.2)^2 =3^2 -2\times 3\times 0.2+0.2^2=9-1.2+0.04 =7.84[/tex].
Again, Using the identity,
[tex]a^2-b^2=(a+b)(a-b)[/tex]
the given quantity can be expressed as
[tex](31^2-29^2)=(31-29)(31+29)=2\times (60)=120[/tex]
Answer:
1) 2.8²
= (2+0.8)² { now it's in the form of (a+b)²}
=2²+2(2)(0.8)+0.8² {because (a+b)²= a²+2ab+b²}
=4+3.2+0.64
=7.84
2) 31²-29²
=(31-29)(31+29) { because, a²-b²= (a-b) (a+b)}
=(2)(60)
=120