Completing The Square

[wiishesssss]

7r ^ 2 - 3r - 6 = 0

So i divided by 7 ..

so i did 7r ^ 2 / 7 , -3r / 7 , -6/7 , and 0/7

so now i have ..

r ^ 2 - 3r/7 = 6/7


(b/2) ^ 2 = ( (3/7) / 2 ) ^ 2 = (3/14) ^ 2


r ^ 2 - 3/7 + (3/14) ^ 2 = 6/7 (3/14) ^ 2

now i know

r ^ 2 - 3/7 + (3/14) ^ 2 is a perfect square trinomial

(r - 3/14) ^ 2


If anyone can help me from that point on i would appreciate it.

 

[skeeter]

7r ^ 2 - 3r - 6 = 0

So i divided by 7 ..

so i did 7r ^ 2 / 7 , -3r / 7 , -6/7 , and 0/7

so now i have ..

r ^ 2 - 3r/7 = 6/7

r² - 3r/7 + (-3/14)² = 6/7 + (-3/14)²

(r - 3/14)² = 6/7 + 9/196

finish up ...


(b/2) ^ 2 = ( (3/7) / 2 ) ^ 2 = (3/14) ^ 2


r ^ 2 - 3/7 + (3/14) ^ 2 = 6/7 (3/14) ^ 2

now i know

r ^ 2 - 3/7 + (3/14) ^ 2 is a perfect square trinomial

(r - 3/14) ^ 2


If anyone can help me from that point on i would appreciate it.

 

[wiishesssss]

got it!

(r - 3/14) ^ 2 = +/- Sq rt. of 177/196

When you take the Sq. Rt. of both sides now you have

r - 3/14 = +/- Sq. Rt. of 177 / 14 (Since the Sq. Rt. of 196 is equal to 14)

Add 3/14 to both sides and the final answer is

r = 3/14 +/- Sq. Rt. of 177 / 14