Solve x2 - 8x - 9 = 0. Rewrite the equation so that it is of the form
x2 + bx = c.

-8 and 9

Add _ to each side x2 – 8x = 9 to complete the square.

16

Now that you have x² - 8x + 16 = 9 + 16, apply the square root property to the equation.

(x - 4)^2 = 25

Choose the solutions to the quadratic equation
x2 – 8x – 9 = 0.

-1 and 9

Answer: d. 39 cmin the diagram, the approximate length of the minor arc de is 39 centimetres.step-by-step explanation: the formula for the length of an arc in a circle is as displayed below.let the length of the minor arc de = xx = 2( pi )r × angle of sector / 360°from this, we will substitute the values given from the problem into the formula to obtain the length of the minor arc de.x = 2( pi )r × angle of sector / 360°r = radius = 25cmpi as an approximate value = 3.14angle of sector = 120°x = 2( 3.14 )( 25 ) × 120° / 360°x = 157 × 1 / 4x = 39.25x = 39 ( rounded to the nearest whole number as an approximate value )