Question

1- As raízes das seguintes funções do 1º grau são
respectivamente:
I. y = 5x + 10
II.
y=-2x + 12
III.
y= 4x + 16
​

Answer 1

Raízes (ou zeros) de uma função são os valores de x que satisfazem y = 0

Para encontrar as raízes de uma função do 1º grau, a ideia é igualar a zero e isolar a incógnita x:

I.

$\begin{array}{l}\sf y=5x+10\\\\\sf 5x+10=0\\\\\sf 5x+10-10=0-10\\\\\sf 5x=-10\\\\\sf \dfrac{\diagdown\!\!\!\!5x}{\diagdown\!\!\!\!5}=-\dfrac{10}{5}\\\\\!\boxed{\sf x=-2}\end{array}$

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II.

$\begin{array}{l}\sf y=-2x+12\\\\\sf -2x+12=0\\\\\sf -2x+12-12=0-12\\\\\sf -2x=-12\\\\\sf -2x\cdot(-1)=-12\cdot(-1)\\\\\sf 2x=12\\\\\sf \dfrac{\diagdown\!\!\!\!2x}{\diagdown\!\!\!\!2}=\dfrac{12}{2}\\\\\!\boxed{\sf x=6}\end{array}$

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III.

$\begin{array}{l}\sf y=4x+16\\\\\sf 4x+16=0\\\\\sf 4x+16-16=0-16\\\\\sf 4x=-16\\\\\sf \dfrac{\diagdown\!\!\!\!4x}{\diagdown\!\!\!\!4}=-\dfrac{16}{4}\\\\\!\boxed{\sf x=-4}\end{array}$

Assim as raízes são respectivamente:

I. – 2

II. 6

III. – 4

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Att. Nasgovaskov