How do you solve #-2x^2 = -162#?

1 Answer
Apr 16, 2017

Answer:

#x=+-9#

Explanation:

#color(blue)"Isolate " x^2" by dividing both sides by " -2#

#(cancel(-2) x^2)/cancel(-2)=(-162)/(-2)#

#rArrx^2=81#

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

#sqrt(x^2)=color(red)(+-)sqrt81#

#rArrx=color(red)(+-)9#

#["Note the " +-" solutions"]#

#color(blue)"As a check"#

Substitute these values into the left side of the equation and if equal to the right side then they are the solutions.

#x=color(red)(+9)to-2xx(color(red)(+9))^2=-2xx81=-162#

#x=color(red)(-9)to-2xx(color(red)(-9))^2=-2xx81=-162#

#rArrx=+-9" are the solutions"#