+0

0
107
3

i need to ask so im trying to do this calculation and it gives me two answers why and how?

Feb 4, 2019

#1
+79
0

What's the calculation?

Feb 5, 2019
#2
0

(3x+3)(x-4)=3(x+1)

Feb 5, 2019
#3
+103709
+1

$$(3x+3)(x-4)=3(x+1)\\ 3x^2-12x+3x-12=3x+3\\ 3x^2-9x-12=3x+3\\ 3x^2-9x-12-3x-3=3x+3-3x-3\\ 3x^2-12x-15=0\\ \text{divide both sides by 3}\\ x^2-4x-5=0\\ (x-5)(x+1)=0$$

now if 2 things multiply together to give 0 then one of them, or both of them, must equal 0.

so

x-5=0      or      x+1=0

x=5         or         x=-1

Feb 5, 2019