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Solve for y

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2 Answers

Hi Lila;
4y2-5=12y
Let's have everything on one side...
4y2-12y-5=0
(2y-3)(2y-3)
Let's FOIL...
FIRST...(2y)(2y)=4y2
OUTER...(2y)(-3)=-6y
INNER...(-3)(2y)=-6y
LAST...(-3)(-3)=9
4y2-6y-6y+9
4y2-12y+9
Obviously, the constant we want is NOT +9.  We want -5...
-5=9-14
4y2-12y+9-14=0
(2y-3)2-14=0
(2y-3)2=14
Square-root both sides...
2y-3=+√14.......2y-3=-√14
2y=3+√14........2y=3-√14
y=(3+√14)/2....y=(3-√14)/2