|
| By using abc formula the value of x as defined by |
| | x[1,2] = | | -b |  | (b2-4ac) | | 2a |
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| Since a = 1, b = 5 and c = 4, |
| we just need to subtitute the value of a,b and c in the abc formula. |
| | So x[1,2] = | - (5) |  | (5)2 - 4 (1) (4) ) | | | 2 (1) |
|
| | Which produce x[1,2] = | -5 |  | (25 - 16) | | | 2 |
|
| | So x[1,2] = | -5 |  | 9 | | | 2 |
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| We got x1 = ( -5 + 3 )/(2) and x2 = ( -5 - 3 )/(2) |
| So we got the answers as x1 = -1 and x2 = -4 |
|
| x2 + 5x + 4 = 0 , factorize the left hand side. |
| ( x + 1 ) ( x + 4 ) = 0 |
| We get following answers x1 = -1 and x2 = -4 |
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| x2 + 5x + 4 = 0 ,divide both side with 1 |
| Which result in x2 + 5x + 4 = 0 , |
| The coefficient of x is 5 |
| We have to use the fact that ( x + q )2 = x2 + 2qx + q2 , assume that q = 5/2 = 2.5 , and q2 = (2.5)2 = 6.25 |
| Next, we have to separate the constant to form x2 + 5x + 6.25 - 2.25 = 0 |
| And it is the same with ( x + 2.5 )2 - 2.25 = 0 |
| Which can be turned into (( x + 2.5 ) - 1.5 ) (( x + 2.5 ) + 1.5 ) = 0 |
| By opening the brackets we will get ( x + 2.5 - 1.5 ) ( x + 2.5 + 1.5 ) = 0 |
| Do the addition/subtraction, and we get ( x + 1 ) ( x + 4 ) = 0 |
| So we have the answers x1 = -1 and x2 = -4 |