To find this answer, we need to multiply 3.57 by 12.
Therefore, 12 planks will cost $42.84.
Answer:
second option
Step-by-step explanation:
Given
+ 6x² + 5 = 0
let u = x², then
u² + 6u + 5 = 0 ← in standard form
(u + 1)(u + 5) = 0 ← in factored form
Equate each factor to zero and solve for u
u + 1 = 0 ⇒ u = - 1
u + 5 = 0 ⇒ u = - 5
Change u back into terms of x, that is
x² = - 1 ( take the square root of both sides )
x = ± 
= ± i ( noting that = i ), and
x² = - 5 ( take the square root of both sides )
x = ± 
= ± 
= ± 
× = ± i
Solutions are x = ± i and x = ± i
Let the value of the vehicle be described by the equation
V = a + bx
where x = number of years since purchase
a,b are constants.
When x = 0, V = $7500. Therefore
a + b*0 = 7500
a = 7500
When x = 7, V = $500. Therefore
7500 + 7b = 500
7b = 500 -7500 = -7000
b = -7000/7 = -1000
The equation is
V = 7500 - 1000x
The slope of this equation is the depreciation rate, and it is -$1000 per year.
Answer: $1000 depreciation per year.
-x - y = 8
2x - y = -1
Ok, we are going to solve this in 2 parts. First we have to solve for one of the variables in one of the equation in terms of the other variable. I like to take the easiest equation first and try to avoid fractions, so let's use the first equation and solve for x.
-x - y = 8 add y to each side
-x = 8 + y divide by -1
x = -8 - y
So now we have a value for x in terms of y that we can use to substitute into the other equation. In the other equation we are going to put -8 - y in place of the x.
2x - y = -1
2(-8 - y) - y = -1 multiply the 2 through the parentheses
-16 - 2y - y = -1 combine like terms
-16 - 3y = -1 add 16 to both sides
-3y = 15 divide each side by -3
y = -5
Now we have a value for y. We need to plug it into either of the original equations then solve for x. I usually choose the most simple equation.
-x - y = 8
-x - (-5) = 8 multiply -1 through the parentheses
-x + 5 = 8 subtract 5 from each side
-x = 3 divide each side by -1
x = -3
So our solution set is
(-3, -5)
That is the point on the grid where the 2 equations are equal, so that is the place where they intersect.
Answer:
-14
Step-by-step explanation:
You've got a(1)=20
a(1) means a(n) when n=1
the sequence is telling you to take the previous value of a(n), which is a(n-1) and subtract 17
then:
a(2) = a(1)-17 = 20 - 17 = 3
a(3) = a(2) - 17 = 3-17 = -14
