+0

# i really dont see this question matching with any of the identities

0
488
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+11854

Use suitable identity to get each of the following products!

vi. (a^2 + b^2) (-a^2 + b^2)

how do i solve it!no identity is matching with this!

Dec 28, 2014

#1
+95361
+15

(a^2 + b^2) (-a^2 + b^2)

\$\$(a^2 + b^2) (-a^2 + b^2)\\\\
=(b^2 + a^2) (b^2 -a^2)\\\\\$\$

Now you can see that it is  the difference of 2 squares. :)

\$\$\\=(b^2)^2-(a^2)^2\\\\
=b^4-a^4\$\$

Does that all makes sense Rosala ?

Dec 28, 2014

#1
+95361
+15

(a^2 + b^2) (-a^2 + b^2)

\$\$(a^2 + b^2) (-a^2 + b^2)\\\\
=(b^2 + a^2) (b^2 -a^2)\\\\\$\$

Now you can see that it is  the difference of 2 squares. :)

\$\$\\=(b^2)^2-(a^2)^2\\\\
=b^4-a^4\$\$

Does that all makes sense Rosala ?

Melody Dec 28, 2014
#2
+11854
+10

umm no...not to me right now!

how did you  just swap everything ......i dont get it!

its like sorting out a ball  of wool!

Dec 28, 2014
#3
+95361
+10

Okay rosala let's look at this.

a+b=b+a              agreed?     (1)

a-b=-b+a              agreed?     (2)

-b+a=a-b              agreed? (It is the same as the one above only in reverse)    (3)

so

\$\${{\mathtt{a}}}^{{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{{\mathtt{b}}}^{{\mathtt{2}}} = {{\mathtt{b}}}^{{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{{\mathtt{a}}}^{{\mathtt{2}}}\$\$            agreed?  (4)

and

\$\${\mathtt{\,-\,}}{{\mathtt{a}}}^{{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{{\mathtt{b}}}^{{\mathtt{2}}} = {{\mathtt{b}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{{\mathtt{a}}}^{{\mathtt{2}}}\$\$         agreed ?  (5)

so

\$\$(a^2 + b^2) (-a^2 + b^2)=(b^2 + a^2) (b^2 -a^2)\\\\\$\$       agreed  (6)

I have numbered all the lines so that you can tell me which ones don't make sense to you.  :)

Dec 28, 2014
#4
+11854
+5

All of them make sense to me Melody!Than you very much!

Dec 28, 2014
#5
+95361
+10

Good - I am glad i could help :)

Dec 28, 2014