11. Use the fact that 19 X 33 = 627 to solve the problems and justify your reasoning
1 answer:
<h2>19 X 33 = 627, justified.</h2>
Step-by-step explanation:
We have,
19 × 33 = 627
Use the fact and justify.
L.H.S. = 19 × 33
= (20 - 1) (20 + 13)
Using the identity,
(x - a)(x + b) = - (a - b)x - ab
Here, x = 20, a = 1 and b = 13
= - (1 - 13)20 - 1(13)
= 400 - (- 12)20 - 13
= 400 + 240 - 13
= 640 - 13
= 627
= R.H.S., justified.
Thus, 19 X 33 = 627, justified.
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Answer:
cm
Step-by-step explanation:
The volume of the box is:
V = height * length * width
V = x*(66 - 2*x)*(90 - 2*x)
V = (66*x - 2*x^2)*(90 - 2*x)
V = 5940*x - 132*x^2 - 180*x^2 + 4*x^3
V = 4*x^3 - 312*x^2 + 5940*x
where x is the length of the sides of the squares, in cm.
The mathematical problem is :
Maximize: V = 4*x^3 - 312*x^2 + 5940*x
subject to:
x > 0
2*x < 66 <=> x < 33
In the maximum, the first derivative of V, dV/dx, is equal to zero
dV/dx = 12*x^2 - 624*x + 5940
From quadratic formula
But , then is not the correct answer.