Question

Aplique o produto da soma pela diferença de dois termos: (y + 0,4).(y-0,4)

a) y² - 0,16
b) y² + 0,16
c) y² + 0,8y + 0,16
d) Nda​

Answer 1

Explicação passo-a-passo:

(y + 0,4).(y - 0,4) = y² - 0,4²

(y + 0,4).(y - 0,4) = y² - 0,16

Letra A

Answer 2

(y + 0,4).(y-0,4)

$\left(y+0.4\right)\left(y-0.4\right):\quad y^2-0.16\\\left(y+0.4\right)\left(y-0.4\right)\\y^2-0.4^2\\0.4^2=0.16$

a)y² - 0,16

$y^2-0.16:\quad \left(y+0.4\right)\left(y-0.4\right)\\y^2-0.16\\y^2-\left(\sqrt{0.16}\right)^2\\\left(y+\sqrt{0.16}\right)\left(y-\sqrt{0.16}\right)\\\sqrt{0.16}=0.4$

b)y² + 0,16

$y^2+0.16:\quad \sqrt{y-0.16},\:-\sqrt{y-0.16}\\\sqrt{y-0.16},\:-\sqrt{y-0.16}\\\sqrt{y-0.16}\::\quad y\ge \:0.16\\-\sqrt{y-0.16}\::\quad y\ge \:0.16\\f\left(y\right)\ge \:0.16\\y^2+0.16:\\\mathrm{Pontos\:de\:interseccao\:com\:o\:eixo\:das\:abscissas\:\left(x\right)\:de\:}y^2+0.16\\\mathrm{Pontos\:de\:interseccao\:com\:o\:eixo\:das\:ordenadas\:\left(y\right)\:de\:}y^2+0.16:\quad \left(0,\:0.16\right)\\\mathrm{Y\:intersepta}:\:\left(0,\:0.16\right)$

c) y² + 0,8y + 0,16

$y^2+0.8y+0.16:\quad \left(y+0.4\right)^2\\y^2+0.8y+0.16\\y^2+0.8y+0.16\mathrm{\:como\:}y^2+2y\cdot \:0.4+\left(\sqrt{0.16}\right)^2\\y^2+2y\cdot \:0.4+\left(\sqrt{0.16}\right)^2\\\left(y+0.4\right)^2\\y= +0,4²\\0.16$

resposta:LETRA (A)