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3 years ago

Solve each of the following equations for the missing variable.

Mathematics

2 answers:

White raven [17]3 years ago

6 0

Answer:

x = -20

Step-by-step explanation:

$- 2.5x - 10 = 40$

Collect like terms and simplify

$- 2.5x = 40 + 10 \\ - 2.5x = 50$

Divide both sides of the equation by -2.5

$\frac{ - 2.5x}{ - 2.5} = \frac{50}{ - 2.5}$

Simplify

$x = - 20$

Ierofanga [76]3 years ago

4 0

The answer for -2.5x-10=40 would be:
x = - 20.

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A cable television compan is laying cable in an area with underground utilities. Two subdivisions are located on opposite sides

Schach [20]

Answer:

Step-by-step explanation:

Given:

Point Q = Q is on the north bank 1200 m east of P $40/m to lay cable underground and $80/m way to lay the cable.

Lets denote T be a point on north bank, therefore, point T is t m east and 100m north of P.

Note that 0 < t < 1200

Distance from P to T using Pythagoras theorem:

PT^2 = PQ^2 + QT^2

PT = √(t²+100²) = √(t²+10,000)

Distance from T to Q:

TQ = 1200 - t

From above, Cable from P to T is underwater, and costs $80/m to lay.

Cable from T to Q is underground, and costs $40/m to lay.

Total cost of the cable:

C(t) = 80√(t²+10,000) + 40(1200 - t)

Cost is at its minimum: when dC/dt = C'(t) = 0 and d^2C/dt^2 = C''(t) > 0

dC/dt = C'(t)

= 80 * 1/2 (t² + 10,000)^(-1/2) × 2t + 40 × (-1)

dC/dt = C'(t)

= 80t/√(t² + 10,000) - 40 = 0

80t/√(t² + 10,000) = 40

80t = 40√(t² + 10,000)

2t = √(t² + 10,000)

square both sides:

4t² = t² + 10,000

3t² = 10,000

t² = 10,000/3

t = 100/√3

≈ 57.735

d^2C/dt^2 =

C''(t) = [80√(t² + 10,000) - 80t × t/√(t²+10,000)] /√(t²+10,000)

C''(t) = [(80(t²+10,000) - 80t²) / √(t²+10,000)] /√(t²+10,000)

C''(t) = 800,000 / (t² + 10,000)^(3/2)

C''(t) > 0 for all t

Therefore C(t) is minimized at t = 100/√3

C(100/√3) = 80√(10,000/3 + 10,000) + 40 × (1200 - 100/√3)

= 80 √(40,000/3) + 48,000 - 4000/√3

= 16000/√3 + 48,000 - 4000/√3

= 48,000 + 12,000/√3

= 48,000 + 4,000√3

= 4000 (12 + √3)

≈ 54,928.20

Minimum cost is $54,928.20

This occurs when cable is laid underwater from point P to point T(57.735 m east and 100m north of P) and then underground from point T to point Q (1200 - 57.735)

= 1142.265 m

5 0

3 years ago

The right expression to calculate how much money will be in an investment account 14 years from now if you deposit $5,000 now an

Svet_ta [14]

Answer:

The expression to compute the amount in the investment account after 14 years is: FV = [5000 ×(1.10)¹⁴] + [3000 ×(1.10)⁸].

Step-by-step explanation:

The formula to compute the future value is:

$FV=PV[1+\frac{r}{100}]^{n}$

PV = Present value

r = interest rate

n = number of periods.

It is provided that $5,000 were deposited now and $3,000 deposited after 6 years at 10% compound interest. The amount of time the money is invested for is 14 years.

The expression to compute the amount in the investment account after 14 years is,

$FV=5000[1+\frac{10}{100}]^{14}+3000[1+\frac{10}{100}]^{14-6}\\FV=5000[1+0.10]^{14}+3000[1+0.10]^{8}$

The future value is:

$FV=5000[1+0.10]^{14}+3000[1+0.10]^{8}\\=18987.50+6430.77\\=25418.27$

Thus, the expression to compute the amount in the investment account after 14 years is: FV = [5000 ×(1.10)¹⁴] + [3000 ×(1.10)⁸].

4 0

3 years ago

Solve and show all work |2×+3| -6=11

mash [69]

Answer:

x = -10; x = 7

Step-by-step explanation:

|2x + 3| - 6 =11

Add 6 to each side.

|2x + 3| = 17

Apply the absolute rule: If |x| = a, then x = a or x = -a.

(1) 2x + 3 = 17 (2) 2x + 3 = -17

Subtract 3 from each side

2x = 14 2x = -20

Divide each side by 2

x = 7 x = -10

Check:

(1) |2(7) + 3| - 6 = 11 (2) |2(-10) + 3| - 6 = 11

|14 + 3| - 6 = 11 |-20 + 3| - 6 = 11

|17| - 6 = 11 |-17| - 6 = 1 1

17 - 6 = 11 17 - 6 = 11

11 = 11 11 = 11

7 0

3 years ago

Tickets for a school play sold for $7.50 for each adult and $3.00 for each child. The total receipts for 118 tickets totaled $69

NeX [460]

X= number of adult tickets
y=number of child tickets.
we can suggest this system of equations:
x+y=118 ⇒x=118-y
7.5x+3y=696

we can solve this system of equations by substitution method:
7.5(118-y)+3y=696
885-7.5y+3y=696
-4.5y=-189
y=-189/-4.5
y=42

x=118-y
x=118-42
x=76

Answer: the number of adult tickets sold was 76.

7 0

3 years ago

A geologist noticed that land along a fault line moved 24.8 centimeters over the past 175 years. On average, how many did the la

fiasKO [112]

It moves .14 centimeters each year

5 0

3 years ago