Solve x²  2x  24 = 0, for x, by completing the square.
x²  2x  24 = 0
x²  2x = 24 {added 24 to each side} x²  2x + 1 = 24 + 1 {took half of the coefficient of x, squared it, and added it to each side} (x  1)² = 25 {wrote the left side as the square of a binomial, added 24 and 1 on the right} x  1 = ±√25 {took the square root of each side} x  1 = ±5 {evaluated the square root of 25 to be 5} x = 1 ± 5 {added 1 to each side} x = 1 + 5 or x = 1  5 {split using the ± sign} x = 6 or 4 6 and 4 are the xintercepts in the graph of the parabola, as shown below. Comments are closed.

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