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rodikova [14]
2 years ago
14

Given the equation 5x − 4 = –2(3x + 2), solve for the variable. Explain each step and justify your process.

Mathematics
1 answer:
blagie [28]2 years ago
3 0
A.
5x-4=-2(3x+2) \ \ \ \ \ \ \ \ \ |\hbox{expand the bracket} \\
5x-4=-2 \times 3x-2 \times 2 \\
5x-4=-6x-4 \ \ \ \ \ \ \ \ \ \ \ \ \ |\hbox{add 6x to both sides} \\
11x-4=-4 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\hbox{add 4 to both sides} \\
11x=0 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\hbox{divide both sides by 11} \\
x=0

B.
3(2x-4)=5x-1 \\
6x-12=5x-1 \\
\boxed{11x-12=-1} \Leftarrow \hbox{the first mistake} \\
11x=11 \\
\boxed{x=11} \Leftarrow \hbox{the second mistake}

Megan's solution isn't correct.
The first mistake: she subtracted 5x from the right-hand side of the equation, but added 5x to the left-hand side.
The second mistake: she divided the right-hand side of the equation by 11, but didn't divide the left-hand side.

The correct solution:
3(2x-4)=5x-1 \ \ \ \ \ \ \ \ \ \ \ |\hbox{expand the bracket} \\
3 \times 2x+3 \times (-4)=5x-1 \\ 6x-12=5x-1 \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\hbox{subtract 5x from both sides} \\
x-12=-1 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \  |\hbox{add 12 to both sides} \\
x=11
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marishachu [46]

Answer:

1. Given

2. Diagonals of a parallelogram bisect each other.

3. Vertical angles are equal.

4. Definition of parallelogram.

5. If lines parallel, then alternate interior angles are equal.

6. ASA

7. CPCTE

Step-by-step explanation:

Statement 1:

The first statement is a parallelogram ABCD, which is already given in the question. So, reason 1 is: Given.

Statement 2:

BT and TD are equal because for a parallelogram, its diagonal bisect each other. Here, BD and AC are the diagonals of parallelogram ABCD. So, the diagonals bisect each other at T. Hence, BT = TD

Statement 3:

Angles 1 and 2 is a pair of vertical angles. A pair of vertical angles are always equal to each other.

Statement 4:

A parallelogram is a quadrilateral whose opposite sides are parallel and equal. Hence, BC ||AD is because of the definition of a parallelogram.

Statement 5:

Angles 3 and 4 is a pair of alternate interior angles. If two lines are parallel, then the alternate interior angles are always equal.

Statement 6:

The triangles BET and DFT are now congruent because:

i.Angle- \angle1=\angle2

ii. Side - BT = TD

iii. Angle - \angle3=\angle4

Therefore, by ASA postulate the two triangles are congruent.

Statement 7:

As the two triangles are congruent, then their corresponding parts are also equal.

So, by CPCTE, ET=FT

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2 years ago
2 Select the correct answer. Consider functions f and g. Which statement gives the best approximation of the solutions of the eq
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Step-by-step explanation: I think not sure.

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2 years ago
Colleen recorded the type of trees in the woods near her house. She counted 20 spruce trees and 50 maple trees. What is the expe
tankabanditka [31]

Answer:

The answer is A \frac{2}{7}

Step-by-step explanation:

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3 years ago
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4 0
3 years ago
How to solve and respond.
son4ous [18]

Step-by-step explanation:

the error:

it is stated that

\frac{5x}{x+7} +\frac{7}{x} = \frac{5x}{x+7} +\frac{7(7)}{x+7}

subtract (5x)/(x+7) from both sides

\frac{7}{x}  = \frac{7(7)}{x+7}

multiply both sides by x + 7

7(x+7) = 49x

7x + 49 = 49x

subtract 7x from both sides to isolate x and its coefficient

49 = 42x

thus, this is only true when 49 = 42x. in order for these two equations to be equal, they must <em>always </em>be true, so this is wrong

the solution:

we want to express 7/x as (something) / (x+7). to do this, we can multiply 7/x  by 1.

anything divided by itself = 1. thus, if we multiply both the numerator and the denominator by something that turns x into (x+7), we can do what we want to do.

(x+7)/x * x turns x into (x+7), so we multiply both the numerator and denominator by (x+7)/x to get

\frac{7}{x} = \frac{7(x+7)/x}{x+7}

substitute this for 7/x in our original problem

\frac{5x}{x+7} +\frac{7(x+7)/x}{x+7} =  \frac{5x}{x+7} +\frac{(7x+49)/x}{x+7} = \frac{5x}{x+7} +\frac{7+49/x}{x+7} = \frac{5x+7+49/x}{x+7}

3 0
2 years ago
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