Question 1200370
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Plug in t = -5
g(t) = 3 - t^2
g(-5) = 3 - (-5)^2
g(-5) = 3 - 25
g(-5) = -22


Plug in t = 6
g(t) = 3 - t^2
g(6) = 3 - 6^2
g(6) = 3 - 36
g(6) = -33


Subtract the results
g(6) - g(-5) = -33 - (-22) = -33 + 22 = <font color=red>-11</font>


<font color=red>The net change is -11.</font>
It means the output has gone down by 11 units when going from g(-5) = -22 to g(6) = -33. 
Use a vertical number line to see why this is the case.
{{{
drawing(400, 200, -5,5,-36,-19,
line(0,-35-3,0,-20+3),
line(0.2,-35,-0.2,-35),
line(0.2,-30,-0.2,-30),
line(0.2,-25,-0.2,-25),
line(0.2,-20,-0.2,-20),
locate(-1,-34.5,"-35"),
locate(-1,-29.5,"-30"),
locate(-1,-24.5,"-25"),
locate(-1,-19.5,"-20"),

blue(circle(0,-22,0.06)),
blue(circle(0,-22,0.08)),
blue(circle(0,-22,0.10)),
blue(circle(0,-22,0.12)),
blue(circle(0,-22,0.14)),
blue(locate(0.3,-21.5,"-22")),

blue(circle(0,-33,0.06)),
blue(circle(0,-33,0.08)),
blue(circle(0,-33,0.10)),
blue(circle(0,-33,0.12)),
blue(circle(0,-33,0.14)),
blue(locate(0.3,-32.5,"-33")),

red(arc(1.2,-27.5,2,10.5,270,450)),
red(line(1.2,-33,1.8,-33)),
red(line(1.2,-33,1.5,-31)),
red(locate(2.5,-27.5,matrix(1,2,"Move","11"))),
red(locate(2.5,-28.8,matrix(1,2,"units","down")))
)
}}}
You can think of -22 as being 22 feet below sea level, aka 22 feet underwater.
Move 11 feet further down and you will arrive at the marker -33 which represents being 33 feet underwater.
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