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astra-53 [7]
3 years ago
5

Which of the following points is the solution of the quadratic equation:3x^2-5x-2=0​

Mathematics
1 answer:
Maslowich3 years ago
7 0

Answer:

x1 = 2

x2 = -1/3

Step-by-step explanation:

3x^2-5x-2=0

D=25-4*(-2)*3 = 25 + 24 = 49 --> sqrt 49 = 7

x1 = 5 + 7 / 2*3 =   2

x2 = 5 - 7 / 2*3 =  -1/3

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Please explain with working!!! Find the set of values of x that satisfy the inequality 9x^2-15x<6
Oksi-84 [34.3K]

Answer:

-1/3

Step-by-step explanation:

When solving a quadratic inequality, first solve it normally like you would for a normal quadratic equation. We have:

9x^2-15x

Ignore the less than sign and replace it with an equal sign and solve the quadratic for its zeros:

9x^2-15x=6

Subtract 6 from both sides:

9x^2-15x-6=0

Divide everything by 3:

3x^2-5x-2=0

Factor. Find two numbers that equal (3)(-2)=-6 that add up to -5.

-6 and 1 works. Thus:

3x^2-6x+x-2=0\\3x(x-2)+1(x-2)=0\\(3x+1)(x-2)=0

Find the x using the Zero Product Property:

3x+1=0 \text{ or }x-2=0\\x=-1/3\text{ or }x=2

Now, we need to replace the equal signs with symbols again. To do so, we need to test which symbol to place. Let's do the first zero first.

So, the first zero is:

x=-1/3

Assume that the correct symbol is >. Thus,

x>-1/3

Now, pick any number that is greater than -1/3. I'll pick 0 since it's the easiest. Now, plug 0 back into the very original inequality. If it works, then the sign is correct, if it doesn't, then simply use the opposite one. Therefore:

9x^2-15x

0 is indeed less than six, so our first correct solution is:

x>-1/3

For the second one, do the same thing. We have:

x=2

Assume that the correct symbol is <. Thus:

x

Again, pick any number less than 2. I'm going to use 0. Plug 0 back into the original equation

9x^2-15x

Again, this is correct. Therefore, x<2 is also the correct inequality.

So together, we have:

x>-1/3 \text{ and } x

Together, we can write them as:

-1/3

(Note that we don't need to worry about the "or equal to" part since the original inequality didn't have it.)

6 0
3 years ago
One small tank takes twice as long to fill a tank as a larger pipe does. If it takes the two pipes 40 minutes to fill the tank w
Gala2k [10]
Um... it'll take each pipe 80 mins, bcz if together they take that long, then to find the pipes time separately, you just multiply it by two to show it doing the work the other pipe did as well. Is that what you wanted??

8 0
3 years ago
Need help desperately T~T
babunello [35]
As you can see, angle 5 and angle 6 are supplementary.  And angle 5 and angle 3 are congruent because they are alternate interior angles.  

So it will be
x+2 = 180- x+3 
                         move x over from the right to the left
2x+2 = 183
                         move 2 over from the left to the right
2x = 181
                          divide by 2
x= 90.5

and angle 3 and angle 1 are vertical angles so they are congruent.  Using the angle 3 formula to solve for the answer:

90.5+3 =93.5

When angles are congruent, their measures are congruent, therefore, measure of angle 1 is 93.5
4 0
4 years ago
I need help with help on the one with the pink circle
podryga [215]

Answer:

15°

Step-by-step explanation:

The line in the middle of the triangle divides it into two triangles.  These two triangles are equal.  You can see this because the given angle (90°) is equal for both sides, and the bottom sides (23) are also equal to each other.  

Since the triangles are equal, this means that the given angle of 75° also applies to the other side.  The total degrees a triangle can have is 180°.  Use the given angles to solve for the unknown angle.

75° + 90° + x = 180°

165° + x = 180°

x = 15°

The angle measure will be 15°.

4 0
4 years ago
Samantha has 14 yards of ribbon. She wraps 12 presents and uses 5/6 yards of ribbon to decorate each present. The total amount o
Lesechka [4]
Samantha will have approximately 2.3-2.4 yards of ribbon left.
3 0
3 years ago
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