# Cant solve distance formula problem.

• Apr 23rd 2012, 04:44 PM
Kanderson
Cant solve distance formula problem.
(0, b),(3,1); d = 5 Solve for b. I must be stupid or something. I keep getting 15, 17.
• Apr 23rd 2012, 05:02 PM
syedmaheen
Re: Cant solve distance formula problem.
sqr root((3-0)^2)+)(1-b)^2) =5
((3-0)^2)+)(1-b)^2) = 5^2
1-2b+b^2=9
b^2-2b-8=0
b^2 -4b +2b -8=0
b(b-4)+2(b-4)=0
(b-4)(b+2)=0
b=4,-2.
• Apr 23rd 2012, 05:06 PM
Kanderson
Re: Cant solve distance formula problem.
Are you sure, my calculator keeps giving me 5, -3 Your probably right.
• Apr 23rd 2012, 05:39 PM
syedmaheen
Re: Cant solve distance formula problem.
No calculator is right,and the one below me is right,i just flipped halfway through the problem,but essentially thats how you do it.
• Apr 23rd 2012, 06:06 PM
skeeter
Re: Cant solve distance formula problem.
\$\displaystyle (3-0)^2 + (1-b)^2 = 5^2\$

\$\displaystyle 9 + (1 - 2b + b^2) = 25\$

\$\displaystyle b^2 - 2b - 15 = 0\$

\$\displaystyle (b - 5)(b + 3) = 0\$

\$\displaystyle b = 5\$ , \$\displaystyle b = -3\$
• Apr 24th 2012, 05:39 AM
HallsofIvy
Re: Cant solve distance formula problem.
Quote:

Originally Posted by syedmaheen
sqr root((3-0)^2)+)(1-b)^2) =5
((3-0)^2)+)(1-b)^2) = 5^2

So 9+ 1- 2b+ b^2= 25
Subtracting 9 from both sides, 1- 2b+ b^2= 16, not 9.

Quote:

1-2b+b^2=9
b^2-2b-8=0
b^2 -4b +2b -8=0
b(b-4)+2(b-4)=0
(b-4)(b+2)=0
b=4,-2.