Question

Answer 1

\(\Leftrightarrow3x+15+x^2+2x+1-x^2-1=0\)

\(\Leftrightarrow5x+15=0\)

\(\Leftrightarrow5x=-15\)

\(\Leftrightarrow x=-3\)

Answer 2

x=-3

Answer 3

\(\Leftrightarrow3\left(x+5\right)+\left(x+1\right)^2-\left(x^2+1\right)=0\)

\(\Leftrightarrow3x+15=0\)

\(\Leftrightarrow3x=-15\Leftrightarrow x=-5\)

Answer 4

<=> 3x + 15 + x² + 2x + 1 - x² - 1 = 0

<=> 5x + 15 = 0

<=> 5x = -15

<=> x = -3