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# 2x^2-8x+3=0 use quadratic formula

need help I know that 1/2, 3/2 should be the answer but when I work it out I dont get that please help me understand. where I am going wrong. thank you

### 2 Answers by Expert Tutors

Jim S. | Physics (and math) are fun, reallyPhysics (and math) are fun, really
4.7 4.7 (189 lesson ratings) (189)
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Hi Roseland,

checking 1/2 and 3/2 ,,,,these are not roots

1.2x2-8x+3=0
2.x2-4x=-3/2……….divide both sides by 2 and subtract 3/2 from both sides
3.x2-4x+4=5/2 ……. Add 1/2 of the coefficient of x squared to both sides
4.(x-2)2=5/2  ………..the left hand side is now a perfect square
5.x1=2+(5/2)1/2      x2=2-(5/2)1/2 ……….solve for x1 and x2 the two roots

This process is called completing the square

Jim
Francisco E. | Francisco; Civil Engineering, Math., Science, Spanish, Computers.Francisco; Civil Engineering, Math., Sci...
5.0 5.0 (1 lesson ratings) (1)
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2x^2-8x+3 = 0 Quadratic solution is x= (-b ±√(b^2 - 4*a*c))/2*a
plugging in the formula we obtain:
x1= (8+(64 - 4*3*2)^0.5)/2*2 = (8+6.32)/4 = 14.32/4 =  3.58
The x2 will be obtained using the negative sign after -b
X2 = 0.42