SOLUTION: How do I plug my answer into the equation to check my answer, by using paper and pencil not the calculator? 10x^2+40=80x 10x^40-80x=80x-80x=0 10x^2-80x+40=0 -80+-sqrt((80)^2-

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: How do I plug my answer into the equation to check my answer, by using paper and pencil not the calculator? 10x^2+40=80x 10x^40-80x=80x-80x=0 10x^2-80x+40=0 -80+-sqrt((80)^2-      Log On


   

Question 411279: How do I plug my answer into the equation to check my answer, by using paper and pencil not the calculator?
10x^2+40=80x
10x^40-80x=80x-80x=0
10x^2-80x+40=0
-80+-sqrt((80)^2-4(10)(40))/(2(10))
-80+-sqrt(6400-1600)/(20)
-80+-sqrt(4800)/(20)
-80+-sqrt((100(4)(12))/(20)
-80+- 10(2) sqrt(12)/(20)
-80+- 20 sqrt(12)/(20)
-40+- 1 sqrt(3)/(5)
-40+- sqrt (3)/(5)
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
How do I plug my answer into the equation to check my answer, by using paper and pencil not the calculator?
10x^2+40=80x
10x^40-80x=80x-80x=0
10x^2-80x+40=0
========================== Simplify it here
x^2 - 8x + 4 = 0 **** It's +8, -b/2a
x = +8/2 ± sqrt(64 - 16)/2
= 4 ± 2sqrt(3)
-----------------
-80+-sqrt((80)^2-4(10)(40))/(2(10))
-80+-sqrt(6400-1600)/(20)
-80+-sqrt(4800)/(20)
-80+-sqrt((100(4)(12))/(20)
-80+- 10(2) sqrt(12)/(20)
-80+- 20 sqrt(12)/(20)
-40+- 1 sqrt(3)/(5)
-40+- sqrt (3)/(5)