Question

Use a suitable identity (x+3) (x+3)​

Answer 1

a^2 + b^2 =[ a + b ]× [a + b] so your and is x^2+3^2

Answer 2

$(x + 3)(x + 3) \\ = (x + 3)^{2} \\ = {(x)}^{2} \times 2 \times x \times 3 + {(3)}^{2} \\ = {x}^{2} + 6x + 9 \\( using)(a+b) 2 = a2 + b2 + 2ab$