Second part?

Question

Solve the following quadratic by completing the square.

X^2 + 9 x – 10 = 0


Solve above by using the quadratic formula. Show work. Graph the roots on a number line.

Answer 1

you can factor the equation and get:

(x + 10) (x - 1) = 0

therefore x = -10 or 1

Answer 2

Completing the square:

x^2 + 9x - 10 = 0

x^2 +9x = 10

(x + 9/2)^2 - (9/2)^2 = 10

(x + 9/2)^2 -(81/4) = 10

(x + 9/2)^2 - 20.25 = 10

(x + 4.5)^2 = 30.25

x + 4.5 = + or - sq.rt. 30.25 = + or - 5.5

x = 5.5 - 4.5 or (-5.5) - 4.5

x = 1 or -10

(2) Using the quadratic formula:
You have a = 1, b = 9 and c = -10

x = { -9 +/- Sq. rt.[9^2 - (4*1*-10)}/2*1

x = {-9+/- sq.rt. [81 + 40]}/2

x = (-9 + 11)/2 or (-9-11)/2

x = 1 or -10 as was obtained by using completing the square.

(3) Draw the number line. Mark the origin 0. Mark equal spaced points to the right of 0. These are +, label point 1. Mark equal spaced points to the left of 0 and label -10.

Note: I think this is what you are asking in the final part unless you mean to sketch the graph and show where it crosses the x axis when y = 0.