At which approximate x-value are these two equations equal
y = √1 - x^2
y = 2x - 1

9514 1404 393

  x = 0.8

Step-by-step explanation:

If you mean y = √(1 -x²), then the curves cross at x=0.8.

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If you equate the y-expressions, then square both sides, you have ...

  √(1-x²) = 2x-1

  1 - x² = (2x -1)² = 4x² -4x +1

  0 = 5x² -4x . . . . . subtract the left-side expression

  x(5x -4) = 0   ⇒   x = 0, or x = 4/5

The x=0 solution is extraneous.

The two equations are equal at x = 4/5.