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stellarik [79]
3 years ago
12

A student solved 3/x−4=x/7 in six steps, as shown.

Mathematics
2 answers:
Rudiy273 years ago
7 0

Answer:

A. The student solved the equation correctly.

Step-by-step explanation:

We have been given a student's work to solve the equation \frac{3}{x-4}=\frac{x}{7}. We are asked to chose accurate interpretation of the student's work.

Step 1: Multiply both sides by (x-4).

\frac{3}{x-4}(x-4)=\frac{x}{7}(x-4)

3=\frac{x(x-4)}{7}

Step 2: Multiply both sides by 7.

3\times 7=\frac{x(x-4)}{7}\times 7

21=x(x-4)

Step 3: Distribute x on right ride.

21=x\cdot x-x\cdot 4

21=x^2-4x

Step 4: Subtract 21 from both sides.

21-21=x^2-4x-21

0=x^2-4x-21

Step 5: Factor by splitting the middle term.

0=x^2-7x+3x-21

0=(x-7)(x+3)

Step 6: Use zero product property.

(x-7)=0, (x+3)=0

x=7,x=-3

Since student's work is correct, therefore, option A is the correct choice.

Stolb23 [73]3 years ago
5 0

Answer:

Option A.

Step-by-step explanation:

The given equation is

\dfrac{3}{x-4}=\dfrac{x}{7}

Step 1: Multiply both sides by (x-4).

3=\dfrac{x(x-4)}{7}

Step 2: Multiply both sides by 7.

21=x(x-4)

Step 3: Using distributive property.

21=x^2-4x

Step 4: Isolate all terms on one side.

0=x^2-4x-21

Step 5: Find factors by splitting the middle term.

0=x^2-7x+3x-21

0=x(x-7)+3(x-7)

0=(x-7)(x+3)

Step 6: Using zero product property, we get

x=-3, x=7

It means student solved the equation correctly.

Therefore, the correct option is A.

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Which of the following expressions is equal to -12 ?
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Simplify:<br> (4p3 + 6p2 – 7) – (8p? – 7 – 3p)
Kipish [7]

Answer:

4p3 + 6p2 - 8p - 7

Step-by-step explanation:

Reformatting the input :

Changes made to your input should not affect the solution:

(1): "p2"   was replaced by   "p^2".  1 more similar replacement(s).

STEP

1

:

Equation at the end of step 1

 (((4 • (p3)) +  (2•3p2)) -  7) -  8p

STEP

2

:

Equation at the end of step

2

:

 ((22p3 +  (2•3p2)) -  7) -  8p

STEP

3

:

Checking for a perfect cube

3.1    4p3+6p2-8p-7  is not a perfect cube

Trying to factor by pulling out :

3.2      Factoring:  4p3+6p2-8p-7

Thoughtfully split the expression at hand into groups, each group having two terms :

Group 1:  -8p-7

Group 2:  4p3+6p2

Pull out from each group separately :

Group 1:   (8p+7) • (-1)

Group 2:   (2p+3) • (2p2)

3.3    Find roots (zeroes) of :       F(p) = 4p3+6p2-8p-7

Polynomial Roots Calculator is a set of methods aimed at finding values of  p  for which   F(p)=0  

Rational Roots Test is one of the above mentioned tools. It would only find Rational Roots that is numbers  p  which can be expressed as the quotient of two integers

The Rational Root Theorem states that if a polynomial zeroes for a rational number  P/Q   then  P  is a factor of the Trailing Constant and  Q  is a factor of the Leading Coefficient

In this case, the Leading Coefficient is  4  and the Trailing Constant is  -7.

The factor(s) are:

of the Leading Coefficient :  1,2 ,4

of the Trailing Constant :  1 ,7

Let us test ....

  P    Q    P/Q    F(P/Q)     Divisor

     -1       1        -1.00        3.00    

     -1       2        -0.50        -2.00    

     -1       4        -0.25        -4.69    

     -7       1        -7.00       -1029.00    

     -7       2        -3.50        -77.00    

     -7       4        -1.75        3.94    

     1       1        1.00        -5.00    

     1       2        0.50        -9.00    

     1       4        0.25        -8.56    

     7       1        7.00        1603.00    

     7       2        3.50        210.00    

     7       4        1.75        18.81    

Final result :

 4p3 + 6p2 - 8p - 7

5 0
2 years ago
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