[tex]Solution,\mathrm{Expand}\:\left(3a^2-7xy\right)\left(3a^2+7xy\right):\quad 9a^4-49x^2y^2[/tex]
[tex]Steps:[/tex]
[tex]\left(3a^2-7xy\right)\left(3a^2+7xy\right)[/tex]
[tex]\mathrm{Apply\:Difference\:of\:Two\:Squares\:Formula:\:}\left(a-b\right)\left(a+b\right)=a^2-b^2,\\a=3a^2,\:b=7xy,\\\left(3a^2\right)^2-\left(7xy\right)^2[/tex]
[tex]\mathrm{Simplify}\:\left(3a^2\right)^2-\left(7xy\right)^2,\\\left(3a^2\right)^2,\\\mathrm{Apply\:exponent\:rule}:\quad \left(a\cdot \:b\right)^n=a^nb^n,\\3^2\left(a^2\right)^2,\\\left(a^2\right)^2,\\\mathrm{Apply\:exponent\:rule}:\quad \left(a^b\right)^c=a^{bc},\\a^{2\cdot \:2},\\\mathrm{Refine},\\a^4,\\3^2a^4[/tex]
[tex]\left(7xy\right)^2,\\\mathrm{Apply\:exponent\:rule}:\quad \left(a\cdot \:b\right)^n=a^nb^n,\\7^2x^2y^2,\\3^2a^4-7^2x^2y^2,\\\mathrm{Refine},\\9a^4-49x^2y^2[/tex]
[tex]\mathrm{The\:Correct\:Answer\:is\:9a^4-49x^2y^2}[/tex]
[tex]\mathrm{Hope\:This\:Helps!!!}[/tex]
[tex]\mathrm{-Austint1414}[/tex]
