Question

Calcule o valor numérico da expressão algébrica abaixo quando x = 4. x + 2x + √x URGENTE

Answer 1

$x=4x+2x+\sqrt{x}\\\\x=6x+\sqrt{x}\\\\-5x=\sqrt{x}\\\\(-5x)^2=(\sqrt x)^2\\\\25x^2=x\\\\25x^2-x=0\\\\x(25x-1)=0\\\\\cdot x=0\\\\\cdot25x-1=0\to 25x=1\to x=\dfrac{1}{25}$

Testemos os dois resultados:

$x=0:\\\\0=2(0)+4(0)+\sqrt0\\\\0=0+0+0\\\\0=0\\\\\text{Verdadeiro}$

$x=\dfrac{1}{25}:\\\\\\\dfrac{1}{25}=4\left(\dfrac{1}{25}\right)+2\left(\dfrac{1}{25}\right)+\sqrt{\left(\dfrac{1}{25}\right)}\\\\\\\dfrac{1}{25}=6\left(\dfrac{1}{25}\right)+\dfrac15\\\\\\\dfrac{1}{25}=\dfrac{6}{25}+\dfrac{5}{25}\\\\\\\dfrac{1}{25}=\dfrac{11}{25}\\\\\text{Falso}$

Portanto,

x=0