How do you solve #3x^2 - 123 = 0#?

2 Answers
Jun 5, 2016

Answer:

#x=±sqrt41#

Explanation:

The first step is to take out a common factor of 3.

#3x^2-123=0rArr3(x^2-41)=0#

now #x^2-41=0rArrx^2=41#

Taking the 'square root' of both sides

#rArrsqrt(x^2)=±sqrt41rArrx=±sqrt41#

Jun 5, 2016

Answer:

#x=+-sqrt41#

Explanation:

Isolate #x# to find its value

#color(blue)(3x^2-123=0#

Add #123# both sides

#rarr3x^2-123+123=0+123#

#rarr3x^2=123#

Divide both sides by #3#

#rarr(cancel3x^2)/cancel3=123/3#

#rarrx^2=41#

Take the square root of both sides

And also remember that,when taking the square root of a number,it can be a positive or negative number

Positive or negative - #+-#

#rarrsqrt(x^2)=+-sqrt41#

#color(green)(rArrx=+-sqrt41#