ElectricPavlov

...because I misread the Q.    ~ EP

As long as we are ' fixing things'      'conjunction' ....or'contraction'?   

Example

1   (3a +2)(a-4)            the  numbers   2   and -4   must multiply to equal  '-8'  

2    (15x+3)( 2x-1)        again.....the   3  and  -1    multiply to -3   and the 15 and 2 multiply to 30

3     This one is factored as far as it can be

4    4 (a^2 -4a +4) - 81

       4a^2-16a+16 - 81

       4 a^2-16a-65          

Deleted.

At time t=0   the object will be at its highest point....the point where it started its fall

  substitute t= 0 in to the equation  

    h(t) = - 16(0)^2 + 900 = 900 ft

 The object will hit the ground when the equation is EQUAL to 0....

    0 = -16t^2 + 900

    900 = 16t^2

900/16 = 56.25= t^2     so t=sqrt(56.25) = 7.5 seconds to hit the ground.

Using law of sines

20/sin45 = BC/sin 30

sin30 * 20/sin45 = BC

1/2 * 20/(sqrt2/2) =

10 * 2/ sqrt2  20/ sqrt2 = 20 sqrt2/2 = 10 sqrt2

You're welcome! 

(x-4)^2 = 25     sqrt both sides

x-4 = +- 5

x = 4 +-5

x = 9 or -1

x^2 +12x     - 11           Let's kinda 'complete the square'

x^2 + 12x  + 36    -36  -11

(x+6)^2  -47

sqrt6  *  sqrt 75 =

sqrt6  * sqrt(25*3)=

5 *  sqrt6 * sqrt 3 =

5* sqrt(6*3)

5 sqrt(18)

5 sqrt(9*2)

5(3)sqrt2 = 15 sqrt 2  

sqrt12 - sqr3 = sqrt(4*3)-sqrt3 = 2 sqrt3 -sqrt3 = (1)sqrt3 = sqrt3