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gulaghasi [49]
3 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]3 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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What is the equation of the line passing through the points (3,6) and (2,10)
andrezito [222]

Answer: y= - 4x+18

Step-by-step explanation:

Equation: y=mx+b

***remember: b is the y-intercept and m is the slope.

m=\frac{y2-y1}{x2-x1}

3= x1

2= x2

6= y1

10=y2

m=\frac{10-6}{2-3}= \frac{4}{1}= -4

m=-4

Now we have y=-4x+b , so let's find b.

You can use either (x,y) such as (3,6) or (2,10) point you want..the answer will be the same:

   (3,6). y=mx+b or 6=-4 × 3+b, or solving for b: b=6-(-4)(3). b=18.

   (2,10). y=mx+b or 10=-4 × 2+b, or solving for b: b=10-(-4)(2). b=18.

Equation of the line: y=-4x+18

3 0
3 years ago
What is the difference of 35- (-8)
Dennis_Churaev [7]

35-(-8)=35+8=43

~~~~~~~~

6 0
3 years ago
Read 2 more answers
Sandra deposited $2,500 into a simple interest account.
MakcuM [25]

Answer:

240$

Step-by-step explanation:

we know that

The simple interest formula is equal to

I=P(rt)

where

I is the Final Interest Value

P is the Principal amount of money to be invested

r is the rate of interest  

t is Number of Time Periods

in this problem we have

Sandra

t = 1 year

I= $75

P= $2,500

r= ?

substitute in the formula above

75=2,500 (r(1))

solve for r

r=75/2,500)

r= 0.03

Convert to percentage form

r= 0.03 * 100 = 3%

Ron

t=1 year

I = ?

P= 8,000

r= 0.03

substitute in the formula of interest

I = 8,000(0.03 *1)

I = $240

8 0
3 years ago
If RT = 6 and RS = 9, then RX =<br> A - sqrt(54)<br> B - 13.5<br> C - 7.2<br> D - 4
wolverine [178]

Answer:

Option D RX=4 units

Step-by-step explanation:

we know that

<em>In the right triangle RTS</em>

The cosine of angle TRS is equal to

cos(TRS)=RT/RS

substitute

cos(TRS)=6/9 -----> equation A

<em>In the right triangle RTX</em>

The cosine of angle TRX is equal to

cos(TRX)=RX/RT

substitute

cos(TRX)=RX/6 -----> equation B

∠TRS=∠TRX -----> is the same angle

Match equation A and equation B

6/9=RX/6

RX=6*6/9=4 units

5 0
3 years ago
What is an explicit formula for the geometric sequence 64,16,4,1,... where the first term
olya-2409 [2.1K]

Answer:

A

Step-by-step explanation:

The explicit formula for a geometric sequence is

f(n) = f(1) (r)^{n-1}

where f(1) is the first term and r the common ratio

Here f(1) = 64 and r = \frac{f(2)}{f(1)} = \frac{16}{64} = \frac{1}{4} , then

f(n) = 64 (\frac{1}{4}) ^{n-1} → A

7 0
3 years ago
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