Use completing the square to solve for x in the equation (x + 7) (x minus 9) = 25.
x = –4 or 6
x = –2 or 14
x = 1 plus-or-minus StartRoot 89 EndRoot
x = 1 plus-or-minus StartRoot 87 EndRoot

x = 1 ±√89

The correct option is C.

Step-by-step explanation:

To solve the equation; (x + 7(x-9) = 25, we will follow the steps below;

First, we will open the bracket

x² - 9x +  7x  - 63 = 25

x² - 2x  - 63 = 25

Add 63 to both-side of the equation

x² - 2x -63 + 63 = 25 + 63

x² - 2x = 88

We can now proceed to solve using the completing the square method.

Add the square of (-1) to both-side of the equation

x² - 2x + (-1)²= 88 + (-1)²

Factorize the left-hand side of the equation and simplify the right-hand side of the equation

(x - 1)² = 88 + 1

(x - 1)² = 89

Take the square root of both-side of the equation

√(x - 1)² = ±√89

x - 1 =±√89

Add 1 to both-side of the equation

x - 1+1 = 1 ±√89

x = 1 ±√89

c

Step-by-step explanation:

Use completing the square to solve for x in the equation (x + 7) (x minus 9) = 25.

x = –4 or 6

x = –2 or 14

x = 1 plus-or-minus StartRoot 89 EndRoot

x = 1 plus-or-minus StartRoot 87 EndRoot

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m

add an !

step-by-step explanation: