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Vadim26 [7]
3 years ago
5

Solve x2 = 12x – 15 by completing the square. Which is the solution set of the equation? (negative 6 minus StartRoot 51 EndRoot

comma negative 6 + StartRoot 51 EndRoot) (negative 6 minus StartRoot 21 EndRoot comma negative 6 + StartRoot 21 EndRoot) (6 minus StartRoot 51 EndRoot comma 6 + StartRoot 51 EndRoot) (6 minus StartRoot 21 EndRoot comma 6 + StartRoot 21 EndRoot)
Mathematics
2 answers:
Brrunno [24]3 years ago
4 0

Answer:

the answer is d

Step-by-step explanation:

Amanda [17]3 years ago
3 0

Answer:

LAST OPTION: (6-\sqrt{21},6+\sqrt{21})

Step-by-step explanation:

1. Subtract 12x from both sides of the equation:

x^2-12x= 12x- 15-12x\\\\x^2-12x=-15

2. Since b=12:

(\frac{b}{2})^2=(\frac{12}{2})^2=(6)^2

3. Now can complete the square. Add (6)^2 to both sides of the equation:

x^2-12x+6^2=-15+6^2

4. Simplifying:

(x-6)^2=21

5. Solve for "x":

\sqrt{(x-6)^2}=\±\sqrt{21}\\\\x-6=\±\sqrt{21}\\\\x=6\±\sqrt{21}\\\\x_1=6+\sqrt{21}\\\\x_2=6-\sqrt{21}

6. The solution set is:

(6-\sqrt{21},6+\sqrt{21})

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Lori buys a $400 certificate deposit that earns 1.8% interest compounded monthly how much will a cd be worth in six years
Firlakuza [10]

Answer:

$1445.11

Step-by-step explanation:

The formula to use would be:

F=P(1+r)^t

Where

F is the future amount (what we want to find)

P is the present (principal) amount (this is 400)

r is the rate of interest, monthly (1.8% or 0.018)

t is the time in months (6 years = 6 * 12 = 72)

Now substituting, we get:

F=P(1+r)^t\\F=400(1+0.018)^{72}\\F = 400(1.018)^{72}\\F=1445.11

After 6 years, the CD will be worth $1445.11

8 0
3 years ago
Mark is planning to run in a 10-km race he will have to run 1 4/5 km uphill, 2 7/10 km downhill, and the rest of the race on lev
777dan777 [17]
<span>Uphill distance = 1 4/5 = 9/5 = 18/10 km Downhill Distance = 2 7/10 = 27/10 km Total Uphill and Downhill = 18/10 + 27/10 = 45/10 = 4.5 km Hence total level ground = Total race km - (Uphill + Downhill) =10 - 4.5 = 5.5 km Hence the answer is 5.5 km.</span>
7 0
3 years ago
Solve the following question algebraically. SOMEONE PLEASE HELP ME! ILL MARK THE BRAINLIEST ANSWER!!I’VE TRIED TO FIGURE IT OUT
Delicious77 [7]

Solve for x. Isolate the x. Note the equal sign. What you do to one side, you do to the other. Do the opposite of PEMDAS.

First, multiply 3 to both sides

6(3) = ((x + 2)/3)(3)

18 = x + 2

Finally, isolate the x. Subtract 2 from both sides

18 (-2) = x + 2 (-2)

x = 18 - 2

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7x-3=4x+3 &lt; Answer Please
USPshnik [31]

Answer:

2! Thank it if it was helpful :D

Step-by-step explanation:

7x-4x=3+3

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8 0
2 years ago
Read 2 more answers
How can knowing how to represent proportional relationships in different ways be useful to solving problems
Anna35 [415]

Answer:

  appropriately writing the proportion can reduce or eliminate steps required to solve it

Step-by-step explanation:

The proportion ...

  \dfrac{A}{B}=\dfrac{C}{D}

is equivalent to the equation obtained by "cross-multiplying:"

  AD = BC

This equation can be written as proportions in 3 other ways:

  \dfrac{B}{A}=\dfrac{D}{C}\qquad\dfrac{A}{C}=\dfrac{B}{D}\qquad\dfrac{C}{A}=\dfrac{D}{B}

  Effectively, the proportion can be written upside-down and sideways, as long as the corresponding parts are kept in the same order.

I find this most useful to ...

  a) put the unknown quantity in the numerator

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__

The usual method recommended for solving proportions is to form the cross-product, as above, then divide by the coefficient of the variable. If the variable is already in the numerator, you can simply multiply the proportion by its denominator.

<u>Example</u>:

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Usual method:

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Multiplying by the denominator:

  x = 4(3/2) = 12/2 = 6 . . . . . . saves the "cross product" step

__

<u>Example 2</u>:

  x/4 = 1/2 . . . . we note that "1" is "sideways" from x, so we can rewrite the proportion as ...

  x/1 = 4/2 . . . . . . written with 1 in the denominator

  x = 2 . . . . simplify

Of course, this is the same answer you would get by multiplying by the denominator, 4.

The point here is that if you have a choice when you write the initial proportion, you can make the choice to write it with x in the numerator and 1 in the denominator.

8 0
3 years ago
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