SOLUTION: please help me understand how to solve this equation. it is from a lecture not a homework problem, but I want to understand how he achieved the solution. the equation is 0.4=0.

Algebra ->  Equations -> SOLUTION: please help me understand how to solve this equation. it is from a lecture not a homework problem, but I want to understand how he achieved the solution. the equation is 0.4=0.      Log On


   

Question 1136032: please help me understand how to solve this equation. it is from a lecture not a homework problem, but I want to understand how he achieved the solution.
the equation is 0.4=0.8(vgsq-1.2)^2 solve for vgsq
the answer is vgsq=1.907
I was trying to get the same answer but I got 1.65 after I took the square root of vgsq. please help me understand this algebra step.
Found 3 solutions by math_helper, MathLover1, MathTherapy:
Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!

0.4 = 0.8(vgsq-1.2)^2

Divide both sides by 0.8
0.5 = (vgsq-1.2)^2

Take sqrt of both sides
0.7071 = (vgsq - 1.2)

Add 1.2 to both sides:
0.7071 + 1.2 = vgsq

1.9071 = vgsq

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

0.4=0.8%28vgsq-1.2%29%5E2 solve for vgsq+

0.4=0.8%28vgsq-1.2%29%5E2.....switch sides

0.8%28vgsq-1.2%29%5E2=0.4...both sides multiply by 10
10%2A0.8%28vgsq-1.2%29%5E2=10%2A0.4
8%28vgsq-1.2%29%5E2=4
%28vgsq-1.2%29%5E2=4%2F8
%28vgsq-1.2%29%5E2=1%2F2...........take sqrt of both sides
sqrt%28%28vgsq-1.2%29%5E2%29=sqrt%281%2F2%29
vgsq-1.2=sqrt%281%2F2%29
vgsq=±1%2Fsqrt%282%29+1.2

solutions:
vgsq=1%2F1.414213562373095%2B1.2
vgsq=1.907106781...round to three decimal places
vgsq=1.907

or
vgsq=1%2F-1.414213562373095%2B1.2
vgsq=0.49289321881...round to three decimal places
vgsq=0.493


Answer by MathTherapy(10551) About Me  (Show Source):
You can put this solution on YOUR website!
please help me understand how to solve this equation. it is from a lecture not a homework problem, but I want to understand how he achieved the solution.
the equation is 0.4=0.8(vgsq-1.2)^2 solve for vgsq
the answer is vgsq=1.907
I was trying to get the same answer but I got 1.65 after I took the square root of vgsq. please help me understand this algebra step.
matrix%281%2C3%2C+.4%2C+%22=%22%2C+.8%28VGSQ+-+1.2%29%5E2%29

matrix%281%2C3%2C+.4%2F.8%2C+%22=%22%2C+%28VGSQ+-+1.2%29%5E2%29 ----- Dividing each side by .8

matrix%281%2C3%2C+.5%2C+%22=%22%2C+%28VGSQ+-+1.2%29%5E2%29 

matrix%281%2C3%2C+sqrt%28.5%29%2C+%22=%22%2C+VGSQ+-+1.2%29 ------ Taking the square root of both sides