Question

(x + 9)²- 10x =4 (21+2x)

Answer 1

x2+2.9.1x-10x=84+8x
x2+18x-10x-8x=84
x2+18x-18x=84
x2=84
x=raiz quadrada de +-84
x=+-9,165

Answer 2

(x + 9)²- 10x =4 (21+ 2x)
x² + 2.9x + 81 - 10x = 84 + 8x
x² + 18x + 81 - 10x = 84 + 8x
x² + 18x - 10x + 81 = 84 + 8x
x² + 8x + 81 = 84 + 8x
x² + 8x - 8x = 84 - 81
x² = 3
x = +/- √3

R.: x = + √3 e x = - √3