View Full Version : In the math problem: 9+(y^2) =(y-4)(y-1) What is why and how did you do it ?
budsbrain
Jan 8, 2010, 08:56 AM
In the math problem: 9+(y^2)=(y-4)(y-1) , what is y and how did you solve it ?
Unknown008
Jan 8, 2010, 09:44 AM
In your mah problem, 'y' is a variable.
Since it is an equation of second order (the highest power is two), this type of equation is a quadratic equation.
However, I'm sure that it will simplify in an equation of first order, and you only need some algebraic manipulation to solve for y.
First, expand the brackets on your right. From there on, you should be able to do the rest. Give it a try and post your answer. :)
KISS
Jan 8, 2010, 10:10 AM
It's a trick question. The final form isn't quadratic at all. It's linear, so it's just algebra.
Note that there is a y^2 on the left of the eqn and a Y^2 on the right, so the (y^2)'s disappear.
Once you solve it, I can show you an EASY way. You need to understnd what your doing before using the easy way, but it's been proven here, that it reduces errors.
dinesh_ravi
Mar 22, 2010, 08:06 AM
well,since this is a linear equation and u obviously would know how to do that,I'll just add a little bit information on how to solve quadratic equations because I am really free now :) hahahaha...
well,a quadratic equation has to have this format in it:
ax²+ax+b=0
and there are 2 ways of solving it:
1.using the X method... *basically it's a guessing method where u guess the answers,but this is mainly for simple quadratic equations and it saves times compared to using the formula.
2.using the formula (which is basically your last resort)
1.what u do is u draw an X and u split the squares on the left...
lets take the equation x²+4x+3=0
1,u split the 1st term into 2 but there must be no squares so it both has to have x in it.(its suppose to be one big X by the way it does not have any spaces in between)
x
\ /
X
/ \
x
2.then,u look at the last term in equation (which is always a number without any unknowns)
and u think of all the possible factors that gives u the number... in this case its 3 so all u can think of its 1x3 and 3x1
and u just put it in the right side of the X and u multiply it diagonally and add it together,if u get the number that's in the middle of the equation,that means that's your answer and when you write your answer horizontally,in this case its...
x 1
\ /
X
/ \
x 3
so,when u have inserted your possible answers you have to do trial and error,where you must multiply 1 with x and 3 with x,and u get x and 3x and u have to add the 2 products to get the middle term in the equation,if you don't get the middle term you have to chose other factors and try them.in this example,the answer x and 3x is correct so this is how your answer is written... :
(x+1)(x+3)=0
Interpreting this can be tricky you will have to separate it into 2. which is...
x+1=0 and x+3=0
so you will have 2 possible answers which is either
x=-1 or x=-3...
2.and now for the formula method :)
for this formula you will have to memorize it,. its
x= -b ± √b²-4ac
2a
to determine a,b and c,u must look at the whole equation and extract it from there :)
for example in equation x²-4.5x-5=0
since the first term is ax according to its format,then a=1 and the next is b=-4.5 (your just basically taking the coefficients of the unknown) and c=-5 (do not forget to take the sign along,you could get the wrong answer and lose marks if you missed it)
so then you just substitute it in and split the equation into a plus and a minus :) I'm done hope this info was useful to you all :D