Question

Помогите задача N4. Срочно

Answer 1

$S=a^2=(2 sqrt{80}- sqrt{5})^2=(2 sqrt{16*5}- sqrt{5})^2=(2*4 sqrt{5}- sqrt{5})^2=\\=(8 sqrt{5}- sqrt{5})^2=(7 sqrt{5})^2=49*5=245$