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motikmotik
2 years ago
6

solve the equation by completing the square. x^2 -6x -21=0 if the solution is not a real number enter no solution (ANSWER -2.48

and 8.48 )this is what the lesson says i just dont know how to show this
Mathematics
1 answer:
Alexus [3.1K]2 years ago
3 0

Answer:

see explanation

Step-by-step explanation:

given x² - 6x - 21 = 0 ( add 21 to both sides )

x² - 6x = 21

to complete the square

• add ( half the coefficient of the x-term)² to both sides

x² + 2 (- 3)x +9 = 21 + 9

(x - 3)² = 30 ( take the square root of both sides )

x - 3 = ± \sqrt{30} ( add 3 to both sides )

x = 3 ± \sqrt{30}

x = 3 - \sqrt{30} = - 2.48 ( to 2 dec. places ) or

x = 3 + \sqrt{30} = 8.48 ( to 2 dec. places )


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PSYCHO15rus [73]

Answer:

Please check the explanation.

Step-by-step explanation:

We know the equation

y = kx

k = y/x

where k is the proportionality constant

so,

First ratio can be calculated as

Miles = 45

Hours = 3/4

The ratio = 45 / (3/4)

                = (45 × 4) / 3

                = 180/3

                = 60

Thus, the proportionality constant = 60

Thus, the remaining ratios can be calculated as:

The Pair (135, Hours)

135/Hours = 60

Hours = 135 / 60

           = 27/12

           = 9/4

           = 2.25

Thus, the pair is (135, 2.25)

The Pair (Miles, 3)

Miles/3 = 60

Miles = 60×3

         = 180

The Pair (90, Hours)

90/Hours = 60

Hours = 90 / 60

          = 3/2

          = 1.5

Thus, the complete table:

Miles           45           135           180             90

Hours           3/4          9/4           3                 3/2

Verification:

Miles / Hour =  45/(3/4) = 60

Miles / Hour = 135 / 2.25 =  60

Miles / Hour = 180 / 3 = 60

Miles / Hour  = 90 / 1.5 =  60      

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Answer:

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