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3 years ago

Which question shows the quadratic fomula used correctly to solve 7x^2=9+x for x

Mathematics

1 answer:

ANTONII [103]3 years ago

3 0

Answer:

x = $\frac{-b\pm\sqrt{b^{2}-4ac} }{2a}$

Step-by-step explanation:

We have

7x²=9+x

Subtracting x from both sides, we get

7x²-x=9+x-x

Cancelling out +x and -x from the right side, we get

7x²-x=9

Subtracting 9 from both sides, we get

7x²-x-9=9-9

Cancelling out 9 and -9 from the right side, we have

7x²-x-9 = 0

The above equation is in the form ax²+bx+c=0 where upon comparing we get a= 7 , b = -1 and c= -9

We can solve for x using the below quadratic formula:-

x = $\frac{-b\pm\sqrt{b^{2}-4ac} }{2a}$

Upon solving we'll get two values for x, one positive an the other negative.

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Solve for x, 0 ≤ x ≤2π (2cosx-1)(2sinx+√3 ) = 0

vladimir1956 [14]

Answer:

x = π/3, x = 5π/3, x = 4π/3

Step-by-step explanation:

Let's split the given equation (2cosx-1)(2sinx+√3 ) = 0 into two parts, and solve each separately. These parts would be 2cos(x) - 1 = 0, and 2sin(x) + √3 = 0.

$2\cos \left(x\right)-1=0,\\2\cos \left(x\right)=1,\\\cos \left(x\right)=\frac{1}{2}$

Remember that the general solutions for cos(x) = 1/2 are x = π/3 + 2πn and x = 5π/3 + 2πn. In this case we are given the interval 0 ≤ x ≤2π, and therefore x = π/3, and x = 5π/3.

Similarly:

$\:2\sin \left(x\right)+\sqrt{3}=0,\\2\sin \left(x\right)=-\sqrt{3},\\\sin \left(x\right)=-\frac{\sqrt{3}}{2}$

The general solutions for sin(x) = - √3/2 are x = 4π/3 + 2πn and x = 5π/3 + 2πn. Therefore x = 4π/3 and x = 5π/3 in this case.

So we have x = π/3, x = 5π/3, and x = 4π/3 as our solutions.

5 0

3 years ago

i need help with the last two. I forgot the formula and wondering if you will help me find which one is and isnt a triangle

Nimfa-mama [501]

Answer:

3. D) 26, 7, 31

4. B) 6, 34, 27

Step-by-step explanation:

Both #3 and #4 use the same strategy: the two shorter sides' sum has to be greater than the longer side.

#3:

2 + 8 is 10, which is less than 13. So A wouldn't form a triangle.

12 + 22 is 34, which is the length of the longer side. So B wouldn't form a triangle either.

14 + 18 is 32, which is less than 40. So C wouldn't form a triangle.

7 + 26 is 33, which is greater than 31. So D would form a triangle.

D. 26, 7, and 31 are the only lengths of the ones shown that form a triangle.

#4:

17 + 18 is 35, which is greater than 19. So A would form a triangle.

11 + 22 is 33, which is greater than 25. So C would also form a triangle.

5 + 18 is 23, which is greater than 20. So D would form a triangle.

6 + 27 is 33, which is less than 34. So B wouldn't form a triangle.

B. 6, 34, and 27 are the only lengths of the ones shown that don't form a triangle.

6 0

3 years ago

Please simplify n-2/n^2-4

Doss [256]

Answer:

$\frac{1}{ {n} + {2}}$

Step-by-step explanation:

$\frac{n - 2}{ {n}^{2} - 4} \\ \\ = \frac{n - 2}{ {n}^{2} - {2}^{2} } \\ \\ = \frac{n - 2}{ ({n} + {2})({n} - {2})} \\ \\ = \frac{1}{ {n} + {2}} \\$

8 0

4 years ago

One meteorite weighs 1.8 pounds. A second meteorite weighs 2.35 times as much as the first meteorite weighs. How much does the s

Grace [21]

The answer is 4.23 the second meteorite wieghts 4.23 pounds

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4 years ago

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EastWind [94]

Same I hate tiktoc for showing me happy couples

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3 years ago