Răspuns :
[tex] \green{ \huge \bf{formula:}}[/tex]
[tex] \green{ \bf(a + b) {}^{2} = a {}^{2} + 2ab + {b}^{2} }[/tex]
[tex](x + 7) {}^{2} = x {}^{2} + 2 \times x \times 7 + 7 {}^{2} = \\ = x {}^{2} + 14x + 49[/tex]
[tex] \green{ \huge \bf{formula:}}[/tex]
[tex] \green{ \bf(a + b) {}^{2} = a {}^{2} + 2ab + {b}^{2} }[/tex]
[tex](x + 7) {}^{2} = x {}^{2} + 2 \times x \times 7 + 7 {}^{2} = \\ = x {}^{2} + 14x + 49[/tex]