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vovangra [49]
3 years ago
12

Elimination 4x-7y=5 9x-7y=-15

Mathematics
1 answer:
Afina-wow [57]3 years ago
7 0

Answer:

x = -4

Step-by-step explanation:

To make this easier to explain and easier to solve, we're going to first multiply the second equation of 9x-7y=-15 by -1 to make the y coefficient positive.

This results in -9x+7y=15.

When we line up the two equations on top of each other now, we'll see that both the first and second equations have opposite y coefficients, which is vital for elimination.

The next step is to add the second equation to the first one. Teachers may tell you to subtract, but I find it easier to add if you make the two y coefficients of negative value to each other.

    4x-7y=5

+ -9x+7y=15

___________

   -5x+0y=20, or just -5x=20, because you have successfully eliminated the y         variable.

From there, you're going to solve like a normal equation (divide both sides by -5) toget you x=-4.

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Quality control finds on average that 0.026% of the items from a certain factory are detective. One month, 4000 items are checke
telo118 [61]

Given that 4000 items are checked in one month, let the number of detective items be represented as y.

Quality control finds on average that 0.026% of the items in the factory are detective. This implies that

\text{Number of }\det ective\text{ items = }\frac{\text{0.026}}{100}\times\text{Total number of items checked}

When 4000 items are checked, we have the number of detective items to be evaluated as

\begin{gathered} \text{Number of }\det ective\text{ items = }\frac{\text{0.026}}{100}\times\text{Total number of items checked} \\ y=\frac{0.026}{100}\times4000 \\ \Rightarrow y=1.04 \end{gathered}

Hence, the number of detective items is 1.04.

7 0
1 year ago
Show all steps necessary to verify the trigonometric identity:
vekshin1

Answer:

1+tan2x

Tan2x

=      <u> sec²x  </u>        = <u>Sec²x  </u>       = cosec²x

    Tan²x            ( Sec²x/cosec²x)

Step-by-step explanation:

4 0
3 years ago
Read 2 more answers
On a coordinate plane, how are the locations of the points (1 , -7) and (1 , 7) related?
yan [13]

Answer:

D. Reflection across x-axis

Step-by-step explanation:

When plotting the two points & then connecting the dots, it will not touch y-axis at all - it will be straight line and cross x axis

3 0
3 years ago
In ABC with the right angle at vertex C, sin(b)= (26)/8. What is sin(a)?
Marat540 [252]

Answer:

We can use the Pythagorean theorem and properties of sines, cosines, and tangents to solve the triangle, that is, to find unknown parts in terms of known parts.

Step-by-step explanation:

Pythagorean theorem:   a2 + b2 = c2.

Sines:   sin A = a/c, sin B = b/c.

Cosines:   cos A = b/c, cos B = a/c.

Tangents:   tan A = a/b, tan B = b/a.

4 0
2 years ago
3 = −2∣ 1 — 4 s − 5 ∣ + 3
artcher [175]

Answer:

s=1

Step-by-step explanation:

3=-2(1-4s-5)+3

3=-2+8s+10+3

3=8s+11

3-11=8s

8=8s

8/8=s

s=1

hope it helps you!!

3 0
3 years ago
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