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hoa [83]
3 years ago
10

The reading speed of second grade students in a large city is approximately normal, with a mean of 89 words per minute

Mathematics
1 answer:
laila [671]3 years ago
4 0
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What two numbers multiply to 44 and add up to 12?
djverab [1.8K]
This pattern of question is always coming up. Since we can't easily guess, then let us set up simultaneous equation for the statements.

let the two numbers be x and y.

Multiply to 44.      x*y = 44 ..........(a)

Add up to 12.      x + y = 12 .........(b)

From (b)

y = 12 - x .......(c)

Substitute (c) into (a)

x*y = 44

x*(12 - x) = 44   

12x - x² = 44

-x² + 12x = 44

-x² + 12x - 44 = 0.       

Multiply both sides by -1

-1(-x² + 12x - 44) = -1*0

x² - 12x + 44 = 0.   

This does not look factorizable, so let us just use quadratic formula

comparing to ax² + bx + c = 0, x² - 12x + 44 = 0,  a = 1, b = -12, c = 44 

x = (-b + √(b² - 4ac)) /2a   or (-b - √(b² - 4ac)) /2a


x = (-(-12) + √((-12)² - 4*1*44) )/ (2*1)    

x = (12 + √(144 - 176) )/ 2

x = (12 + √-32 )/ 2

√-32 = √(-1 *32) = √-1 * √32 = i * √(16 *2) = i*√16 *√2 = i*4*√2 = 4i√2

Where i is a complex number.  Note the equation has two values. We shall include the second, that has negative sign before the square root.

x = (12 + √-32 )/ 2      or     (12 - √-32 )/ 2   

x = (12 + 4i√2 )/ 2              (12 - 4i√2 )/ 2 

x = 12/2 + (4i√2)/2                12/2 - (4i√2)/2

x = 6 + 2i√2            or         6 - 2i√2

Recall equation (c):

y = 12 - x, When x = 6 + 2i√2,  y = 12 - (6 + 2i√2) = 12 - 6 - 2i√2 = 6 - 2i√2

When x = 6 - 2i√2,  y = 12 - (6 - 2i√2) = 12 - 6 + 2i√2 = 6 + 2i√2


x = 6 + 2i√2,  y = 6 - 2i√2

x = 6 - 2i√2,  y = 6 + 2i√2

Therefore the two numbers that multiply to 44 and add up to 12 are:

6 + 2i√2 and 6 - 2i√2
8 0
3 years ago
Read 2 more answers
David invested $1000.00. What would that money grow to in 18 months at a 5.5% interest rate?
Dovator [93]
5000.00.interesting rate
4 0
3 years ago
P=s1+s2+s3 solve for s3
tresset_1 [31]

P=s1+s2+s3

Move +s1 to the other side. Sign changes from +s1 to -s1

P-s1=s1-s1+s2+s3

p-s1=s2+s3

Move s2 to the other side. Sign changes from s2 to -s2

p-s1-s2=s2-s2+s3

p-s1-s2=s3

Answer: p-s1-s2=s3

6 0
3 years ago
1÷1+cosa+1÷1_cos a please solve question​
zloy xaker [14]

ok so THIS IS UR ANSWER I THINK PLEASE MAKE ME BRAINLIEST

4 0
3 years ago
Two planes, which are 2235 miles apart, fly toward each other. Their speeds differ by 95 mph. If they pass each other in 3 hours
lora16 [44]

Answer:

325 mph and 420 mph

Step-by-step explanation:

If the speed of the slower plane is x, then the speed of the faster plane is x + 95.

The distance traveled by the slower plane is 3x.

The distance traveled by the faster plane is 3(x + 95).

The total distance is 2235 miles.

3x + 3(x + 95) = 2235

3x + 3x + 285 = 2235

6x = 1950

x = 325

x + 95 = 420

The speed of the planes is 325 mph and 420 mph.

5 0
4 years ago
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