Solve by completing the square: x²-10x = 11 Please help! I've done every other question on my assignment but I've been over and over this ones and can't figure it out!
3 Answers
hala718 | High School Teacher | (Level 1) Educator Emeritus
x^2 -10x =11
Now we will add and subtract [(X's coefficient)/2]^2
We know that X's coefficient is 10
==> Then, we will add (10/2)^2 = 5^2 = 25 to both sides.
==> x^2 -10x +25 = 11 + 25
==> x^2 -10x +25 = 36
Now we will rewrite the expression as a complete square.
==> (x-5)^2 = 36
Now to solve, we will take the square root of both sides.
==> l x -5 l = l6l
==> x-5 = 6 ==> x = 11
==> -(x-5) = 6 ==> -x+5 = 6 ==> -x = 1 ==> x = -1
Then we have two solutions:
x = { -1, 11}
soulet303 | Student, Grade 9 | (Level 2) eNoter
Isn't there an algebra question that some brainac teacher hasn't already answered. It'll be much appreciated if you let me answer one so I don't feel dumb.
zozocbell | Student, Undergraduate | eNotes Newbie
first one is (x-11)(x+1)...so x=11 and x=-1
2nd 1 use +or - b formula google it
3rd dno
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