This expression can be simplified by first distributing the 3x into the parentheses and then multiplying the terms in the second set of parentheses using the distributive property.
Starting with the expression 3x(5+12x)-(6x-1)(6x+1):
= 3x(5) + 3x(12x) - (6x)(6x) - (6x)(1) + (1)(6x) - (1)(1)= 15x + 36x^2 - 36x^2 - 6x + 6x - 1= 15x - 1
Therefore, the simplified expression is 15x - 1.
This expression can be simplified by first distributing the 3x into the parentheses and then multiplying the terms in the second set of parentheses using the distributive property.
Starting with the expression 3x(5+12x)-(6x-1)(6x+1):
= 3x(5) + 3x(12x) - (6x)(6x) - (6x)(1) + (1)(6x) - (1)(1)
= 15x + 36x^2 - 36x^2 - 6x + 6x - 1
= 15x - 1
Therefore, the simplified expression is 15x - 1.