3. Solve `x`
`x^2 -2x-3=0`
3. Solve x
x^2 -2x-3=0 `x = (-b ± sqrt(b^2-4ac))/(2a)`
`x =4 or x=-1`
Use quadratic formula: `x = (-b ± sqrt(b^2-4ac))/(2a)`
where
`a = 1`
`b =-2 `
`c =-3`
substitute `a\ b` and `c` to the quadratic formula, we get
`x = (-(-2) ± sqrt((-2)^2-4(1)(-3)))/(2(1))`
`x = (2 ± 4)/(2)`
`x =4 or x=-1`
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