How do you solve #3-4x^2=-85#?

2 Answers
May 8, 2018

Answer:

#+-sqrt(22)#

Explanation:

Subtract #3# to the other side

#-4x^2 = -88 #

Then, divide both sides by #-4#

#x^2 = 22#

Finally, take the square root of both sides.

#x = +-sqrt(22)#

May 8, 2018

Answer:

Rearrange the expression and you will find that #x=+-4.69#

Explanation:

First, we'll rearrange the expression such that all of the constants are on one side of the expression, and all of the terms directly related to #x# are on the other side:

#cancel(3)-4x^2color(red)(cancel(-3))=-85color(red)(-3)#

#-4x^2=-88#

Now, we'll divide by the coefficient on #x#'s side:

#(cancel(-4)x^2)/color(red)(cancel(-4))=(cancel(-)88)/color(red)(cancel(-)4)#

#x^2=22#

Finally, we'll take the square root of both sides to get the answer:

#sqrt(x^2)=sqrt(22)#

#color(green)(x=+-sqrt(22)=+-4.69#

You have to put the #+-# in because both positive and negative values yield positive answers when squared.