<span>Inflection points are where the function changes concavity. Since concave up corresponds to a positive second derivative and concave down corresponds to a negative second derivative, then when the function changes from concave up to concave down (or vise versa) the second derivative must equal zero at that point. So the second derivative must equal zero to be an inflection point. But don't get excited yet. You have to make sure that the concavity actually changes at that point.</span>
Answer:
<h3>The surface area in square meters that Darren has to paint is

</h3><h3>∴

</h3>
Step-by-step explanation:
Given that Darren is painting a wooden block is a rectangular prism
Its length is 12 cm ,width is 9 cm and height is 5 cm
<h3>To find the surface area in square meters that Darren has to paint :</h3>
Let l be the length, w be the width and h be the height
Then l=12 cm , w=9 cm and h=5 cm
The formula for the Surface area is
A=2(lw+wh+hl) square units
Substitute the values in formula we get,
A=2(12(9)+9(5)+5(12))
=2(108+45+60)
=2(213)
=426
<h3>∴

</h3><h3>∴ the surface area in square meters that Darren has to paint is

</h3>
Yes you can divide fractions using models here is an example
Answer:
The answer is -60 (I believe)
Step-by-step explanation:
3(-10)-5(6)
-30-30 = -30+-30
-30+-30= -60
The answer is -60