Question

Please show me how to solve for Xsquared - 21.75X = -15.75. I have the solution but do not know how to solve it.

Answer 1

`x^2-21.75x=-15.75 \\ x^2-21.75x+15.75=0`

Use the quadratic formula:

`x^2-21.75x+15.75=0 \\ \\ a=1 \\ b=-21.75 \\ c=15.75 \\ b^2-4ac=(-21.75)^2-4 * 1 * 15.75=473.0625-63=410.0625 \\ \\ x=(-b \pm √(b^2-4ac))/(2a)=(-(-21.75) \pm √(410.0625))/(2 * 1)=(21.75 \pm 20.25)/(2) \\ x=(21.75-20.25)/(2) \ \lor \ x=(21.75+20.25)/(2) \\ x=(1.5)/(2) \ \lor \ x=(42)/(2) \\ x=(15)/(20) \ \lor \ x=21 \\ x=(3)/(4) \ \lor \ x=21 \\ \boxed{x=(3)/(4) \hbox{ or } x=21}`