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3 years ago

Solve 9x - 12 - 8x - 3

Mathematics

1 answer:

Igoryamba3 years ago

8 0

X-5

First combine like terms:
X-12-3

Then calculate difference:
X-5

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Please help me with the test

UNO [17]

Answer:

0 2/4 maybe

Step-by-step explanation:

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3 years ago

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In simplest radical form, what are the solutions to the quadratic equation 6 = x2 – 10x? Quadratic formula: x = StartFraction ne

dalvyx [7]

Answer:

x = 5±√31

Step-by-step explanation:

Step 1: Complete the Square

x² - 10x + 25 = 6 + 25

(x - 5)² = 31

Step 2: Solve for x

√(x - 5)² = √31

x - 5 = ±√31

x = 5±√31

And we have our answers!

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3 years ago

Ruth Brown wants to borrow $2,600 for 90 days to pay her real 'estate tax. State Savings and Loan charges 7.25% ordinary interes

podryga [215]

Answer:

Step-by-step explanation:

Ordinary interest rate = principal × rates × ( time / 360)

exact interest rate = principal × rates × ( time / 365)

for states saving and loan of rate 7.25 %

ordinary interest rate = $ 2600 × 0.0725 × ( 90 / 360) = $ 47.125

total amount due after 90 days = $ 2647.125

for Security Bank of 7.5%

exact interest = $2600 × 0.075 × ( 90 / 365) = $ 48.75

amount due after 90 days = $ 2600 + $ 48.75 = $ 2648.75

b) considering the amount to be paid at maturity it is better to borrow state savings and Loan although the difference is not really much.

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3 years ago

If 7 notepads cost $3.15, what is the unit price of the notepads?

vovangra [49]

Answer:

$0.45

Step-by-step explanation:

Unit price is basically the same as unit rate. Unit rate is the cost of one item.

So $3.15 divided by seven is point fourty-five.

6 0

4 years ago

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Suppose the standard deviation of X is 6 and the standard deviation of Y is 8. Answer the following two questions, rounding to t

Darina [25.2K]

Recall that

Var[aX + bY] = a ² Var[X] + 2ab Cov[X, Y] + b ² Var[Y]

Then

Var[3X - 7Y] = 9 Var[X] - 42 Cov[X, Y] + 49 Var[Y]

Now, standard deviation = square root of variance, so

Var[3X - 7Y] = 9×6² - 42×2 + 49×8² = 3376

The general result is easy to prove: by definition,

Var[X] = E[(X - E[X])²] = E[X ²] - E[X]²

Cov[X, Y] = E[(X - E[X]) (Y - E[Y])] = E[XY] - E[X] E[Y]

Then

Var[aX + bY] = E[((aX + bY) - E[aX + bY])²]

… = E[(aX + bY)²] - E[aX + bY]²

… = E[a ² X ² + 2abXY + b ² Y ²] - (a E[X] + b E[Y])²

… = E[a ² X ² + 2abXY + b ² Y ²] - (a ² E[X]² + 2 ab E[X] E[Y] + b ² E[Y]²)

… = a ² E[X ²] + 2ab E[XY] + b ² E[Y ²] - a ² E[X]² - 2 ab E[X] E[Y] - b ² E[Y]²

… = a ² (E[X ²] - E[X]²) + 2ab (E[XY] - E[X] E[Y]) + b ² (E[Y ²] - E[Y]²)

… = a ² Var[X] + 2ab Cov[X, Y] + b ² Var[Y]

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3 years ago