SOLUTION: use the quadratic formula to solve the equation. If necessary, round answers to the nearest hundredth. question 1 : 2a^2-46a+252=0 question 2 : x^2-4x=5 please answer thes

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: use the quadratic formula to solve the equation. If necessary, round answers to the nearest hundredth. question 1 : 2a^2-46a+252=0 question 2 : x^2-4x=5 please answer thes      Log On


   

Question 395154: use the quadratic formula to solve the equation. If necessary, round answers to the nearest hundredth.
question 1 : 2a^2-46a+252=0
question 2 : x^2-4x=5
please answer these . thanks
Found 2 solutions by mananth, jsmallt9:
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
question 1 : 2a^2-46a+252=0
/2
x^2-23x+121=0
x^2-14x-9x+121=0
x(x-14)-9(x-14)=0
(x-14)(x-9)=0
x=14, x=9
question 2 : x^2-4x=5
x^2-4x-5=0
x^2-5x+x-5=0
x(x-5)+1(x-5)=0
(x-5)(x+1)=0
x=5, x=-1
...
m.ananth@hotmail.ca

Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
The solution provided by another tutor does not use the Quadratic Formula as the problem specifies and there is a typographics error in the first solution.

question 1 : 2a%5E2-46a%2B252=0
Dividing both sides by 2 will make the "a", "b" and "c" smaller. This will make the rest of the problem easier:
a%5E2-23a%2B126=0
The Quadratic Formula:
x+=+%28-%28-23%29+%2B-+sqrt%28%28-23%29%5E2+-+4%281%29%28126%29%29%29%2F2%281%29
which simplifies as follows:
x+=+%2823+%2B-+sqrt%28529+-+504%29%29%2F2
x+=+%2823+%2B-+sqrt%2825%29%29%2F2
x+=+%2823+%2B-+5%29%2F2
In long form this is:
x+=+%2823+%2B+5%29%2F2 or x+=+%2823+-+5%29%2F2
x+=+28%2F2 or x+=+18%2F2
x = 14 or x = 9

question 2 : x%5E2-4x=5
One side needs to be zero so we start by subtracting 5 from each side:
x%5E2-4x-5=0
The Quadratic Formula:
x+=+%28-%28-4%29+%2B-+sqrt%28%28-4%29%5E2+-+4%281%29%28-5%29%29%29%2F2%281%29
which simplifies as follows:
x+=+%284+%2B-+sqrt%2816+-+4%281%29%28-5%29%29%29%2F2
x+=+%284+%2B-+sqrt%2816+%2B+20%29%29%2F2
x+=+%284+%2B-+sqrt%2836%29%29%2F2
x+=+%284+%2B-+6%29%2F2
In long form this is:
x+=+%284+%2B+6%29%2F2 or x+=+%284+-+6%29%2F2
x+=+10%2F2 or x+=+%28-2%29%2F2
x = 5 or x = -1