Question

RESOLVA AS EQUAÇAO DO 2 GRAU
7x ao quadrado-21=0


X ao quadrado+9=0

Answer 1

7x^2-21=0
X^2+9=0
7x^2-21=X^2+9
7x^2-21-X^2-9=0
6x^2-30=0
6x^2=30
x^2=30/6
x^2=5
x=raiz5