How do you solve #-2n^2 - 8n + 19 = -3n^2 + 4#?

Question

1214 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-05-12T09:38:34

#n=5, n=3#

#-2n^2 - 8n + 19 = -3n^2 + 4#

Subtract 4 from both sides.
#-2n^2 -8n + 19 - 4 = -3n^2 cancel(+4 - 4)#

#rArr -2n^2 - 8n +15 = -3n^2#

Add 3n^2 to both sides.

#-2n^2 - 8n + 15 + 3n^2 = cancel(-3n^2 + 3n^2)#

#rArr n^2 -8n + 15 = 0 #

Factorise (if possible), if not complete the square or use the quadratic formula.

#(n-5)(n-3)#

Set equal to #0#:

#n-5=0#

#n=5#

#n-3=0#

#n=3#