How do you solve #-4x^2 + x^2 = -36#?

1 Answer
Jul 4, 2016

Answer:

#x=+-2sqrt(3)#

Explanation:

given:#" "color(green)(-4x^2)color(brown)(+x^2)=-36#

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One way of calculating this

We know that#" "+3 + 1 = +4#

So #" -3-1 = -4#

Write #-4x^2# as #-3x^2-1x^2#

Mathematically should be written as #color(green)(-3x^2-x^2)#
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So we know have:

#color(green)(-3x^2-x^2)color(brown)(+x^2)=-36#

But #-x^2+x^2=0# giving

#-3x^2+0=-36#

#-3x^2=-36#

Divide both sides by #-3#

#(-3)/(-3)x^2=(-36)/(-3)#

Divide one negative number by another negative number and you have a positive answer.

But #(-3)/(-3)=+1" and "(-36)/(-3)= + 12#

#1xx x^2=12#

#x^2=12#

Square root both sides

#sqrt(x^2)=sqrt(3xx2^2)#

#x=+-2sqrt(3)#