[tex] \tt (7 - 2y) (7 +2y)[/tex]
By using identinty :
[tex] \large \underline{\boxed{\bf{(a-b)(a+b) = a^2 - b^2}}}[/tex]
[tex] \tt : \implies (7 - 2y) (7 +2y) = (7)^{2} - (2y)^{2}[/tex]
[tex] \tt : \implies (7 - 2y) (7 +2y) = 49 - 4y^{2}[/tex]
[tex] \large \underline{\boxed{\bf{(7 - 2y) (7 +2y) = 49 - 4y^{2}}}}[/tex]
Hence, value of (7 - 2y) (7 +2y) is 49 - 4y².