The given expression is
[tex]3x^2+12x-15=0[/tex]
First, we factor our the number 3.
[tex]3(x^2+4x-5)=0[/tex]
Then,
[tex]x^2+4x-5=0[/tex]
Now, we look for two numbers whose product is 5, and whose difference is 4, those numbers are 5 and 1.
[tex](x+5)(x-1)=0[/tex]
Hence, the solutions are x = -5 and x = 1.
