It works because 7 x 9 x 10 is the same thing as 7 x 90, since 9 x 10 is just 90. So basically he is just writing more but the answer will still be the same.
When you have two squares stacked on top of each other, pretend the angle in the bottom left of the top square is a 90 degree angle, that means that the angle of the square right underneath, also sharing the line, is a 90 degree angle. Or whatever you would need to get it equal to 180, my example was 90/90.
Let the lengths of the sides of the rectangle be x and y. Then A(Area) = xy and 2(x+y)=300. You can use substitution to make one equation that gives A in terms of either x or y instead of both.
2(x+y) = 300
x+y = 150
y = 150-x
A=x(150-x) <--(substitution)
The resulting equation is a quadratic equation that is concave down, so it has an absolute maximum. The x value of this maximum is going to be halfway between the zeroes of the function. The zeroes of the function can be found by setting A equal to 0:
0=x(150-x)
x=0, 150
So halfway between the zeroes is 75. Plug this into the quadratic equation to find the maximum area.
A=75(150-75)
A=75*75
A=5625
So the maximum area that can be enclosed is 5625 square feet.
False -11 is furter on the number line then -1
Answer:
27 ft = 324 inches
Step-by-step explanation:
We want to use dimensional analysis to convert a quantity here
27 ft to inches
Mathematically;
12 inches = 1 ft
so;
x inches = 27 ft
So the number of inches will be 27 * 12 = 324 inches
