6(x-3)-x(x+3)+7(x^2+6)

Question

trouble with combining like terms

Answer 1

6(x-3)-x(x+3)+7(x^2+6)

solve multiplication of parenthesis first 

=(6x-18)+(-x^2-3x)+(7x^2+42)

Remember multiplication of a positive number with a negative number gives you a negative Product. 

 

Combine like terms and solve addition and subtractions 

=7x^2-x^2+6x-3x+42-18

=6x^2+3x+24

Remember that addition of negative an negative numbers becomes a subtraction.

Take the example above:

7x^2-x^2 is the same as

7x^2+ -x^2

-x^2 is the same as -1x^2

thus, 7x^2 + -1x^2 = 6x^2

 

It is a positive result because the largest number in the equation (7) is a positive number.