[tex]\sf{Given : 3tanx + 7 = \dfrac{2}{(1 - sinx)(1 + sinx)}}[/tex]
We know that : (a - b)(a + b) = a² - b²
[tex]\implies \sf{3tanx + 7 = \dfrac{2}{1 - sin^2x}}[/tex]
We know that : 1 - sin²x = cos²x
[tex]\implies \sf{3tanx + 7 = \dfrac{2}{cos^2x}}[/tex]
[tex]\sf{\bigstar \ \ We \ know \ that : \boxed{\sf{\dfrac{1}{cos^2x} = sec^2x}}}[/tex]
[tex]\implies \sf{3tanx + 7 = 2sec^2x}[/tex]
We know that : sec²x = 1 + tan²x
[tex]\implies \sf{3tanx + 7 =2(1 + tan^2x)}[/tex]
[tex]\implies \sf{2 + 2tan^2x - 3 tanx - 7 = 0}[/tex]
[tex]\implies \sf{2tan^2x - 3 tanx - 5 = 0}[/tex]
[tex]\implies \sf{2tan^2x - 5tanx + 2tanx - 5 = 0}[/tex]
[tex]\implies \sf{2tanx(tanx + 1) - 5(tanx + 1) = 0}[/tex]
[tex]\implies \sf{(tanx + 1)(2tanx - 5) = 0}[/tex]
[tex]\implies \sf{tanx = -1 \ (or) \ tanx = \dfrac{5}{2} }[/tex]
