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exis [7]
2 years ago
12

The work of a student to solve the equation 3(3x − 4) = 8 + 2x + 5 is shown below: Step 1. 3(3x − 4) = 8 + 2x + 5 Step 2. 6x − 7

= 13 + 2x Step 3. 6x − 2x = 13 + 7 Step 4. 4x = 20 Step 5. x = 5 In which step did the student first make an error and what is the correct step? (1 point) Step 2, 9x − 12 = 13 + 2x Step 2, 9x − 4 = 2(6 + x + 3) Step 3, 6x + 2x = 13 + 7 Step 3, 6x − 2x = 13 − 7
Mathematics
1 answer:
Mamont248 [21]2 years ago
8 0

Answer:

  (a)  Step 2. 9x -12 = 13 +2x

Step-by-step explanation:

The distributive property says a factor outside parentheses multiplies each term inside parentheses. It is an error to do addition of the factor, or to miss multiplying a term.

In Step 2 of this "solution", the factor of 3 is erroneously <em>added</em> to each coefficent inside parentheses. It should be <em>multiplied</em>.

Correct Step 2: 9x -12 = 13 +2x

__

The rest of the solution should be ...

  Step 3: 9x -2x = 13 +12

  Step 4: 7x = 25

  Step 5: x = 25/7

___

<em>Check</em>

  3(3(25/7) -4) = 8 + 2(25/7) +5

  3((75 -28)/7) = 13 +50/7

  141/7 = 141/7 . . . . . answer checks OK

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Answer:

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5 0
3 years ago
Given: △ABC; AB=BC, m∠BDA = 60°, BD=4 cm, BD ⊥ BA . Find: DC, AC.
vekshin1

Answer:

DC = 10.93 cm ,  AC = 9.8 cm

Step-by-step explanation:

From trigonometry;

⇒ Tan 60 = AB/BD

⇒AB = BD Tan 60 ( where BD = 4 cm )

⇒ AB = 6.93 cm

Also, AB=BC , therefore;

⇒ BC = 6.93 cm

⇒ Cos 60 = BD/AD

⇒ AD = BD/ Cos 60 = 4/Cos 60

⇒ AD = 8 cm

From Pythagoras theorem;

⇒ AC^{2} = AB^{2} + BC^{2} = (6.93)^{2} + (6.93)^{2}

⇒ AC = \sqrt{96.05} = 9.80 cm

⇒ DC = BD + BC = 4 + 6.93

⇒ DC = 10.93 cm

8 0
3 years ago
Which equation represents a parabola that has a focus of (0 0) and a directrix of y = 2
Ilya [14]
The answer is 3 because z to the y a-1
3 0
3 years ago
Read 2 more answers
Simplify the following expressions and remember to pay attention to the signs plz help me
ioda

2 negatives can be converted to a plus sign. -(-x) can be +x or just x.

-54--23

-54+23

<u>23-54=-31</u>

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<u>78+4=82</u>

-48/-6

Now let's pause fer a sec. When a negative is being divided by another negative, the quotient(answer to division problem) becomes a positive.

<u>-48/-6=8</u>

<u></u>

<u>50*-4=-200</u>

---

hope it helps

7 0
3 years ago
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How many possible combinations of 6 numbers?
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 9*8*7*6*5*4 = 60480. Hope this helps !!!!!!!!!!!!!!!!!!!1
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