How do you solve x^2-10x+8=0x210x+8=0 using the quadratic formula?

1 Answer
Feb 29, 2016

x=5+-sqrt(17)x=5±17

Explanation:

11. Determine the aa, bb, and cc values of the equation. Recall that the general quadratic equation written in standard form is: ax^2+bx+c=0ax2+bx+c=0.

x^2-10x+8=0x210x+8=0

color(red)(1)x^21x2 color(orange)(-10)x10x color(blue)(+8)=0+8=0

a=color(red)1color(white)(XXX)b=color(orange)(-10)color(white)(XXX)c=color(blue)(8)a=1XXXb=10XXXc=8

22. Substitute the aa, bb, and cc values into the quadratic formula.

x=(-b+-sqrt(b^2-4ac))/(2a)x=b±b24ac2a

x=(-(color(orange)(-10))+-sqrt((color(orange)(-10))^2-4(color(red)1)(color(blue)8)))/(2(color(red)1))x=(10)±(10)24(1)(8)2(1)

33. Solve for xx.

x=(10+-sqrt(100-32))/2x=10±100322

x=(10+-sqrt(68))/2x=10±682

x=(10+-2sqrt(17))/2x=10±2172

x=(2(5+-sqrt(17)))/(2(1))x=2(5±17)2(1)

x=(color(red)cancelcolor(black)2(5+-sqrt(17)))/(color(red)cancelcolor(black)2(1))

color(green)(x=5+-sqrt(17))

:., x=5+-sqrt(17).