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Nikolay [14]
3 years ago
12

Solve the equation x2 + + 7x= 30

Mathematics
1 answer:
antiseptic1488 [7]3 years ago
8 0

Answer:

x^2+7x=30

x^2+7x-30=0

Here a=1,b=7 and c=-30

Now,

Discriminant(D)=b^2-4ac

=7^2-4×1×(-30)

=49+120=169

By applying Quadratic formula

x=-b+- root over b^2-4ac÷2a

=-7+- root over D ÷ 2×1

=-7 +- root over 169 ÷2

=-7 +- 13 ÷2

Now,

Either x=-7+13÷2=6÷2=3

Or x=-7 -13 ÷2=-20÷2=-10

Hence, ans is (C) x=-10 and x=3

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(7 + 7i)(2 − 2i)
Ostrovityanka [42]

The complex number  -7i into trigonometric form is 7 (cos (90) + sin (90) i) and  3 + 3i in trigonometric form is 4.2426 (cos (45) + sin (45) i)

<h3>What is a complex number?</h3>

It is defined as the number which can be written as x+iy where x is the real number or real part of the complex number and y is the imaginary part of the complex number and i is the iota which is nothing but a square root of -1.

We have a complex number shown in the picture:

-7i(3 + 3i)

= -7i

In trigonometric form:

z = 7 (cos (90) + sin (90) i)

= 3 + 3i

z = 4.2426 (cos (45) + sin (45) i)

\rm 7\:\left(cos\:\left(90\right)\:+\:sin\:\left(90\right)\:i\right)4.2426\:\left(cos\:\left(45\right)\:+\:sin\:\left(45\right)\:i\right)

\rm =7\left(\cos \left(\dfrac{\pi }{2}\right)+\sin \left(\dfrac{\pi }{2}\right)i\right)\cdot \:4.2426\left(\cos \left(\dfrac{\pi }{4}\right)+\sin \left(\dfrac{\pi }{4}\right)i\right)

\rm 7\cdot \dfrac{21213}{5000}e^{i\dfrac{\pi }{2}}e^{i\dfrac{\pi }{4}}

\rm =\dfrac{148491\left(-1\right)^{\dfrac{3}{4}}}{5000}

=21-21i

After converting into the exponential form:

\rm =\dfrac{148491\left(-1\right)^{\dfrac{3}{4}}}{5000}

From part (b) and part (c) both results are the same.

Thus, the complex number  -7i into trigonometric form is 7 (cos (90) + sin (90) i) and  3 + 3i in trigonometric form is 4.2426 (cos (45) + sin (45) i)

Learn more about the complex number here:

brainly.com/question/10251853

#SPJ1

3 0
2 years ago
Is 12.54 greater than 12.539?
Damm [24]

Answer:

yes

Step-by-step explanation:

12.54

>

12.53

reason why is because of the 4>5

8 0
3 years ago
Read 2 more answers
What is -38/-5 as a decimal?
sesenic [268]
Divide -38 by -5
The negatives cancel out since a negative divided by a negative is a positive.
7.6
5 0
3 years ago
Which relation is a function
Marina CMI [18]

Answer:

A.

Step-by-step explanation:

A function is a relation in which every input or value in the domain is paired with exactly one output or value in range.

Draw vertical to check if there is one output for one input.

Hope it is useful...

6 0
2 years ago
What expression is equal to 8 + 2(y + 5)?<br><br> 10y + 50<br> 10y + 5<br> 2y + 13<br> 2y + 18
SVEN [57.7K]

Answer:

2y + 18

Step-by-step explanation:

8 + 2(y + 5)

8 + 2y + 10

2y + 18

6 0
3 years ago
Read 2 more answers
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