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9514 1404 393

  x = 18

Step-by-step explanation:

The parallel lines cut the transversals proportionally.

  (2x -1)/40 = 21/24

  2x -1 = 35 . . . . . . . multiply by 40

  2x = 36 . . . . . . . . add 1

  x = 18  . . . . . . . . . divide by 2

im not quite sure if this is right but i got 5.6 oisutuve

step-by-step explanation:

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15