Answer:
x^2 -81
Step-by-step explanation:
(x+9)(x-9)
FOIL
first x*x = x^2
outer -9x
inner 9x
last -9*9 = -81
Add them together
x^2 -9x+9x -81
Combine like terms
x^2 -81
We need to find the surface area of the solid.
Since it's formed by cubes with edges of 1 meter, each square on the surface of the solid has an area equal to:

Thus, to find its surface area, we need to count the number of squares on its surface, and then multiply this number by 1 meter².
We can see that this solid has two equal latera surfaces (right and left). Each one of them has 17 squares.
Also, the number of squares on the horizontal surfaces is the same on the top and bottom of the solid. Each one of them has 10 squares.
And the vertical surfaces on the front and back of the solid have the same number of squares: 8 squares each.
Then, adding those quantities and multiplying the result by two, we find the total number of squares on the surface of the solid:

Therefore, the surface area of the solid is 70 m².
The mistakes you have are on both letter’s A and B so I wrote a note for you to look back on^^
Hi, so for A. You need to rewrite 19 as -19
And for B. You need to rewrite 15 as -15
Otherwise everything seems correct
Answer:
33 years
Step-by-step explanation:
I think you might have made a typo, but it would still be 33 if the mean age stays the same.
Answer:
this question doesn't make sense. Isn't there a speed?