I don’t know what the answer is, help plz

Answer:
[tex]10x^{2}[/tex] + 20x + 50
Step-by-step explanation:
[tex]a^{2} + b^{2} = c^{2} \\(x+7)^{2} + (3x+1)^{2} = 10x^{2} + 20x + 50[/tex]