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Natalka [10]
3 years ago
12

12x−5y=−20 y=x+4 x=x=x, equals y=y=y, equals

Mathematics
1 answer:
aksik [14]3 years ago
8 0

Answer:

The solution is (0, 4)

Step-by-step explanation:

Please pay attention to the first two equations and drop the last two:

12x−5y=−20 y=x+4 x=x=x, equals y=y=y   should ideally be:

12x−5y=−20

y=x+4

Let's find x.  Substitute x + 4 for y in the first equation, obtaining:

12x - 5(x + 4) = -20

Carrying out the indicated multiplication, we get:

12x - 5x - 20 = -20, or 7x = 0

If x = 0 then y must be 0 + 4, or 4.  

The solution is (0, 4)

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Let $a$ and $b$ be nonzero real numbers such that
algol [13]
<h3>Answer:   -7/2</h3>

=========================================================

Explanation:

Let's expand out (2 - 7i)(a + bi) using the FOIL rule

(2 - 7i)(a + bi) = 2a + 2bi - 7ai - 7bi^2

(2 - 7i)(a + bi) = 2a + 2bi - 7ai - 7b(-1)

(2 - 7i)(a + bi) = 2a + 2bi - 7ai + 7b

(2 - 7i)(a + bi) = (2a+7b) + (2bi-7ai)

(2 - 7i)(a + bi) = (2a+7b) + (2b-7a)i

We're told the result is purely imaginary. What this means is that the real part (2a+7b) is zero, while the imaginary part (2b-7a) is nonzero. If both are zero, then we have 0+0i = 0 which is purely real.

For example, the complex numbers 0-7i and 0+2i are purely imaginary.

Let's use the fact that 2a+7b must be zero to do the following steps:

2a+7b = 0

2a = -7b

a = -7b/2

a/b = -7/2 which is the final answer

We must check to see if 2b-7a is nonzero

2b - 7a = 2b - 7(-7b/2)

2b - 7a = 2b + 24.5b

2b - 7a = 26.5b

The result is nonzero if and only if b is nonzero. Luckily we're told b is nonzero at the top of the problem. So we don't have any worries that (2b-7a) is zero.

Therefore, (2a+7b) + (2b-7a)i will be purely imaginary with a/b = -7/2

------------------

A concrete example:

Let a = -14 and b = 4

a/b = -14/4 = -7/2

(2-7i)(a+bi) = (2-7i)(-14+4i) = 0 + 106i which is purely imaginary.

I'll let you do the steps in expanding that out using the FOIL rule.

4 0
1 year ago
A carpenter has a 6 foot long board, he wants to cut the board into pieces that are 4/5 foot long
Artyom0805 [142]
You need to divide 6 by 4/5.
6÷4/5
6 x 5/4
30/4
7 2/4 = 7 1/2 answer
5 0
3 years ago
Please help me branniest
Julli [10]

Answer:

just add the powers to get 6 to the 10 power


3 0
3 years ago
Can someone please help me?
Radda [10]

Answer:

44 degrees

Step-by-step explanation:

Triangles ABC and DBC are congruent (as said in the question), that would make the corresponding parts of the two triangles congruent.

4 0
3 years ago
Read 2 more answers
Please help ASAP and explain the answer, thank you
jonny [76]

Answer:

Step-by-step explanation:

1) x² - 8x + 5 = 0

2) No subtract 5 from both sides

x² - 8x + 5 - 5 = 0 - 5

x² - 8x  = -5

3) Now find (8/2) = 4. Add 4² = 16 to both sides

x² - 8x + 16 = -5 + 16

x² - 8x + 16 = 11

4) (x - 4)²  = 11

5) Take square root both sides

x - 4 = ±√11

x = 4 ±√11

6 0
3 years ago
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