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gulaghasi [49]
2 years ago
11

For what value of "a" will the product shown below have a purely imaginary value? (Show work please)

Mathematics
1 answer:
MakcuM [25]2 years ago
5 0
If you expand out the brackets you get this,

(4+5i)(a+2i) = 4a + (5a)i + 8i - 10

The -10 comes from 5i * 2i.
Squaring i becomes -1.

Let's group the real stuff together,
and imaginary separately,

(4a - 10) + (5a + 8)i

For this to be purely imaginary,
the real part needs to be zero.

Therefore 4a - 10 = 0

Solve for a.
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Factor the polynomial expression 15x^2 - 2x - 8
AVprozaik [17]

Answer:

(3 x + 2) (5 x - 4)

Step-by-step explanation:

Factor the following:

15 x^2 - 2 x - 8

Factor the quadratic 15 x^2 - 2 x - 8. The coefficient of x^2 is 15 and the constant term is -8. The product of 15 and -8 is -120. The factors of -120 which sum to -2 are 10 and -12. So 15 x^2 - 2 x - 8 = 15 x^2 - 12 x + 10 x - 8 = 5 x (3 x + 2) - 4 (3 x + 2):

5 x (3 x + 2) - 4 (3 x + 2)

Factor 3 x + 2 from 5 x (3 x + 2) - 4 (3 x + 2):

Answer: (3 x + 2) (5 x - 4)

4 0
2 years ago
The area of a rectangle is 5x^3+19+6x-18 with length x + 3. Using synthetic division, what is the width of the rectangle?
adell [148]
               5  19    6  -18
        -3     
                    -15 -12   18

                 5    4   -6    0

Therefore, the width is 5x^2 + 4x - 6
8 0
2 years ago
Read 2 more answers
A coordinate grid with 2 lines. The first line is labeled y equals negative StartFraction 7 over 4 EndFraction x plus StartFract
KengaRu [80]

Answer:

1) (2.2, -1.4)

2) (1.33, 1)

Step-by-step explanation:

Question 1)

Two lines, with their corresponding equations are given and we have to find the solution to the system of equations.

The given lines are:

Equation of Line 1:

y=\frac{-7}{4}x+\frac{5}{2}

This line passes through the points: (0, 2.5) , (2.2, -1.4)

Equation of Line 2:

y=\frac{3}{4}x-3

This line passes through the points (0, -3) , (2.2, -1.4)

By looking at the graph/given data we have to find the solution of these linear equations.

Remember that the solution of linear equations is an ordered pair, through which both the lines pass i.e. the point at which both the given lines intersect is the solution of the linear equations.

From the given data we can see that both the lines pass through one common point, (2.2, -1.4). Since, both lines pass through this point, this means this is the point of intersection of the lines and hence there solution.

So, the answer to this questions is (2.2, -1.4)

Question 2)

The given equations are:

y = 1.5x - 1                                        Equation 1

y = 1                                                  Equation 2

We can solve these equations by method of substitution.

Substituting the value of y from Equation 2, in Equation 1, we get:

1 = 1.5x - 1

1 + 1 = 1.5x

2 = 1.5x

x = 2/1.5

x = 1.33

y = 1

Thus, the solution of the given linear equations is (1.33, 1)

5 0
1 year ago
Read 2 more answers
The tip jar at a sandwich shop has been found to have a dollar value 0.65ℎ +1.25, where ℎ is the number of hours since the shop
DedPeter [7]

Answer:

The intial value is 1.25

Step-by-step explanation:

7 0
2 years ago
The sum of the interior angles of a convex polygon is the same as the sum of its exterior angles. What type of polygon is it?
RideAnS [48]
A parallelogram.

All the angles in a parallelogram must add up to 360° as well as the exterior angles.

Hope that helps!

:D®
7 0
1 year ago
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