3D - 2

How would I finish this equation to make it a perfect square? 4d squared -16d + __?

I learned this awhile ago but I forgot how to factor and now we are doing it again in pre-calculus.

Public Comments

1. 64 take the -16, cut it in half, and square it.
2. What you are doing is PST(perfect square Trinomial ) wherein the middle term should be equal to 2x the product of the sq. root of the 1st and last terms. Therefore the last term is 16 How to check: 4dsq. -16d + 16 Get the sq. of the first and last terms which are 2d and 4. Then multiply both, the product is 8d then when you multiply it by to it becomes 16d. Remember that the sign of the middle term does not matter in this case. The sol. is trial and error Definitely 64 is wrong because 4dsq. - 16d + 64 When you check it the sq. root of 4dsq. is 2d then the sq. root of 64 is 8 and when you multiply both 16d will be the answer but you still need to multiply it by 2 therefore the middle term will be 32d