1. The first step is complete the square; you would take 5x^2+20x (from the original question and factor out the 5 just from 5x^2+20x (not including the negative 10), so now you’re left with y=5(x^2+4x)-10.
2. Now, you need to completely complete the square; so, you would take the 2nd number factored in the bracket (in this case, 4) and multiply by ½ and then square it; (4 x ½) = 2^2 = 4. You’re now left with y=5(x^2+4x+4__)-10.
3. After, you have got to minus the value that you have just found inside the brackets as well (-4) because then it will balance it out making it equal, so that it won’t mess with the original values. Now, we’ve got y=5(x^2+4x+4-4)-10.
4. To complete the square, we have got to multiply the 5 by -4 to get it out of the bracket so we can form a perfect square; 5(x^2+4x+4)-20-10.
5. We are now able to simplify it by simplifying the numbers out of the bracket (-20-10) and forming the perfect square; we now will get the final solution, 5(x+2)^2-30. |