How do you solve #2x ^ { 2} - 18= 0#?

2 Answers
Jim G.
Mar 30, 2018

#x=+-3#

Explanation:

#"add 18 to both sides"#

#2x^2cancel(-18)cancel(+18)=0+18#

#rArr2x^2=18#

#"divide both sides by 2"#

#rArrx^2=9#

#color(blue)"take the square root of both sides"#

#sqrt(x^2)=+-sqrt9larrcolor(blue)"note plus or minus"#

#rArrx=+-3#

skad
Mar 30, 2018

Add 18, divide by 2, square root answer

Explanation:

Add 18, as you want to set #2x^2# equal to a number

#2x^2 = 18#

Divide it by 2, leaving only #x^2#

#x^2 = 9#

Square root the number

#x = sqrt(9)#
#x = 3# or #x = -3#

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