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VashaNatasha [74]
3 years ago
14

Numbers that add to -0.5 and multiply to 1

Mathematics
1 answer:
Oliga [24]3 years ago
7 0
Short Answer
There are two numbers
x1 = -0.25 + 0.9682i   <<<< answer 1
x2 = - 0.25 - 0.9582i   <<<< answer 2 
 
I take it there are two such numbers.
Let one number = x
Let one number = y

x + y = -0.5    
y = - 0.5 - x       (1)
xy = 1               (2)

Put equation 1 into equation 2
xy = 1
x(-0.5 - x) = 1
-0.5x - x^2 = 1               Subtract 1 from both sides.
-0.5x - x^2 - 1 = 0          Order these by powers
-x^2 - 0.5x -1 = 0           Multiply though by - 1
x^2 + 0.5x + 1 = 0         Use the quadratic formula to solve this.

\text{x = }\dfrac{ -b \pm \sqrt{b^{2} - 4ac } }{2a}

a = 1
b = 0.5
c = 1


\text{x = }\dfrac{ -0.5 \pm \sqrt{0.5^{2} - 4*1*1 } }{2*1}

x = [-0.5 +/- sqrt(0.25 - 4)] / 2
x = [-0.5 +/- sqrt(-3.75)] / 2
x = [-0.25 +/- 0.9682i

x1 = -0.25 + 0.9682 i
x2 = -0.25 - 0.9682 i

These two are conjugates. They will add  as x1 + x2 = -0.25 - 0.25 = - 0.50.

The complex parts cancel out.  Getting them to multiply to 1 will be a little more difficult. I'll do that under the check.

Check
(-0.25 - 0.9682i)(-0.25 + 0.9682i)
Use FOIL
F:-0.25 * -0.25 = 0.0625
O: -0.25*0.9682i
I: +0.25*0.9682i
L: -0.9682i*0.9682i = - 0.9375 i^2 = 0.9375

Notice
The two middle terms (labled "O" and "I" ) cancel out. They are of opposite signs.

The final result is 0.9375 and 0.0625 add up to 1
 
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Answer:

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Step-by-step explanation:

<u><em>When finding the answer, we can notice they already give the values for the needed answers.</em></u>

<u><em>The first one requires f(x) and g(x). At the beginning of the question it shows that </em></u><u><em>f(x) is equal to 2x+3. Meaning we can plug in 2x+3 for f(x).</em></u>

<u><em>The same goes for g(x). At the begginning of the question, it shows that </em></u><u><em>g(x) is equal to 4x-2. Meaning we can plug in 4x-2 for g(x).</em></u>

<u><em>f(x) * g(x)</em></u>

<u><em>(2x+3) * (4x-2)</em></u>

<u><em>To find the answer, we need to </em></u><u><em>distibute the 2x+3 into 4x-2</em></u><u><em>.</em></u>

<u><em>To distribute, we do </em></u><u><em>:</em></u>

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<u><em>Next we distibute the 3</em></u>

<u><em>3 * 4x  =  12x        and        3 * -2 = -6</em></u>

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<u><em>Now we can combine them by</em></u><u><em> adding like terms </em></u><u><em>to get the asnwer:</em></u>

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<u><em>The first answer is </em></u><u><em>8x^2 + 8x -6</em></u>

<u><em>Second question:</em></u>

<u><em>Since we already know the values for f(x) and g(x), all we have to do is </em></u><u><em>plug in the values</em></u><u><em>.</em></u>

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<u><em>2x - 4x = -2x</em></u>

<u><em>3 - (-2) = 5</em></u>

<u><em>The second answer is </em></u><u><em>-2x + 5</em></u>

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