Bonjour,
[tex] \frac{1}{4 {}^{2} } + \frac{1}{( - 3) {}^{2} } [/tex]
[tex] = \frac{1}{16} + \frac{1}{9} [/tex]
[tex] = \frac{9 \times 1}{9 \times 16} + \frac{16 \times 1}{16 \times 9} [/tex]
[tex] = \frac{9 + 16}{144} [/tex]
[tex] = \frac{25}{144} [/tex]
