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

Question

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

Answer 1

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

Answer 2

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