First, we must turn this equation ( x2 + 3 ) ( x2 - 2 ) = x^2 - 2 into ax2+bx+c=0 form. |
| ( x2 + 3 ) ( x2 - 2 ) = x2 - 2 , expand the left hand side. |
| <=> x2 ( x2 - 2 ) + 3 ( x2 - 2 ) = x2 - 2 |
| <=> ( x4 - 2x2 ) + ( 3x2 - 6 ) = x2 - 2 |
| <=> x4 + x2 - 6 = x2 - 2 , move everything in the right hand side to the left hand side. |
| <=> x4 + x2 - 6 - ( x2 - 2 ) = 0 |
| <=> x4 + x2 - 6 + ( - x2 + 2 ) = 0 |
| <=> x4 - 4 = 0 |
The equation x |
| By using abc formula the value of x as defined by |
| | x2[1,2] = | | -b |  | (b2-4ac) | | 2a |
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| As a = 1, b = 0 and c = -4, |
| we need to subtitute a,b,c in the abc formula, with those values. |
| | So x2[1,2] = | - (0) |  | (0)2 - 4 (1) (-4) ) | | | 2 (1) |
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| | So x2[1,2] = | 0 |  | (0 + 16) | | | 2 |
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| | So x2[1,2] = | 0 |  | 16 | | | 2 |
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| We can get x12 = ( 4 )/(2) and x22 = ( - 4 )/(2) |
| We can get x12 = 2 and x22 = -2 |
| The equation x4 - 4 = 0 , have four roots : |
| | Root 1 : x1 = | x12 | = | 2 | = 1.4142135623731 | | Root 2 : x2 = | x22 | = | -2 | = 1.4142135623731i | | Root 3 : x3 = - | x12 | = - | 2 | = -1.4142135623731 | | Root 4 : x4 = - | x22 | = - | -2 | = -1.4142135623731i |
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| x4 - 4 = 0 ,divide both side with 1 |
| So we get x4 - 4 = 0 , |
| The coefficient of x is 0 |
| We have to use the fact that ( x + q )2 = x2 + 2qx + q2 , assume that q = 0/2 = 0 , and q2 = (0)2 = 0 |
| Which means we can turn the equation into x4 - 4 = 0 |
| So we will get ( x2 )2 - 4 = 0 |
| And it is the same with (( x2 ) - 2 ) (( x2 ) + 2 ) = 0 |
| By using the associative law we get ( x2 - 2 ) ( x2 + 2 ) = 0 |
| Just add up the constants in each brackets, and we get ( x2 - 2 ) ( x2 + 2 ) = 0 |
| We got x12 = 2 and x22 = -2 |
| The equation x4 - 4 = 0 , have four roots : |
| | Root 1 : x1 = | x12 | = | 2 | = 1.4142135623731 | | Root 2 : x2 = | x22 | = | -2 | = 1.4142135623731i | | Root 3 : x3 = - | x12 | = - | 2 | = -1.4142135623731 | | Root 4 : x4 = - | x22 | = - | -2 | = -1.4142135623731i |
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