How do you solve 8x-10=x^2-7x+3 using the quadratic formula?

2 Answers
Aug 24, 2017

Convert the given equation into standard quadratic form and then apply the quadratic formula to get
color(white)("XXX")x=(15+-sqrt(173))/2

Explanation:

The standard quadratic form is
color(white)("XXX")color(red)ax^2+color(blue)bx+color(green)c=0
with solutions given by the quadratic formula
color(white)("XXX")x=(-color(blue)b+-sqrt(color(blue)b^2-4color(red)acolor(green)c))/(2color(red)a)

Converting the given equation:
color(white)("XXX")8x-10=x^2-7x+3
into standard form results in
color(white)("XXX")color(red)1x^2+color(blue)(""(-15))x+color(green)(13)=0

Plugging the coefficient values into the quadratic formula gives the result shown in the answer above.

Aug 24, 2017

Answers(to 3 d.p.): 0.924 and 14.077

Explanation:

Since you have

8x - 10 = x^2 - 7x+3,

You transfer the numbers on the left hand side to the right in order to get the normal order: ax^2 ± bx ± c.

8x - 10 = x^2 - 7x +3

If you add 10 on both sides, you eliminate the -10 on the left and bring it to the right.

8x - 10 +10 = x^2 - 7x +3 + 10

= 8x = x^2 - 7x +13

Do the same for the 8x until you get 0.

8x -8x = x^2 - 7x +13-8x

= 0 = x^2 - 15x +13

= x^2 - 15x +13

So now that you have everything in order, you can input the coefficients into the quadratic formula:

x=(-(-15) ± sqrt(225 - 52))/(2×1)

=(15 ± sqrt(173))/(2×1)

=(15 ± sqrt(173))/2

=(15 + sqrt(173))/2

=14.077

=(15 - sqrt(173))/2

=0.924

Hope this helps!