Answer:
L = 5 m
Step-by-step explanation:
The ladder, the vertical wall and the ground form a right triangle. We call A and B the ends points of the ladder ( at the wall, and the ground)
If we call L the lenght of the leadder, we get
L² = y² + x²
Taking derivatives on both sides of the equation
0 = 2y Dy/dt + 2x Dx/dt
We know that Dy/dt = - 0,675 m/s (is sliding down , is decreasing)
And when x = 3 m Dx/dt = 0,9 m/s
So we can get y
0 = 2y*( -0,675) + 2*3*0,9
1,35y = 5,4
y = 5.4 /1,35 ⇒ y = 4
And L² = y² + x² ⇒ L = √ (4)² + (3)² ⇒ L √16 + 9
L = 5 m
Answer:
22.50
Step-by-step explanation:
874 = 900
38 = 40
900 / 40 = 22.5 = $22.50
Answer:
A.
Step-by-step explanation:
C and D do not create any x² terms when doing the multiplications. so, they are out.
B stands for (a+b)×(a-b) = a² - b².
so, that would give us a "-4" at the end and is not fitting to the "+4" term at the end of the original expression.
that leaves us with A.
let's verify :
(4x+2i)(4x-2i)
it follows the same rule as B :
(a+b)(a-b) = a² - b²
a = 4x
b = 2i
you remember, i = sqrt(-1).
so, we get
(4x)² - (2i)² = 16x² - 4×(sqrt(-1))² = 16x² - 4×(-1) = 16x²+4
bingo !
This polynomial is a difference of two squares.
A difference of two squares factors into the product of a sum and a difference.