From the original equation x^2+10x-8=0, move the loose number on the other side. Your new equation will be x^2+10x=8. Moving an element from one side to another reverses its sign. From -8 to +8. Then take half of the x-term and square it and add it on both sides. X-term is 10x and 10 is the number, half of it is 5 then square of 5 is 25. Add 25 on both side. Your new equation will be x^2+10x+25=8+25. Then complete the square form of the left side of the equation, (x+5)^2=33. Square root both side then you will get x+5=squareroot of 33. Your x = -5 plus/minus squareroot of 33.
A) the angle is 105 because its supplemental with the 75 degree angle B) the angle's 75 because the given 75 degree angle is correspondant C) 105 again because they are supplemental
