MeghaP wrote:
AshokGmat2016 wrote:
As the curve cuts the x-axis at (h,0) and (k,0). Therefore h,k are the roots of the quadratic equation.
For the quadratic equation is in the form of ax^2+bx+c=0,
The product of the roots =c/a= 256/1=256 and the sum of the roots = -b/a=-b
256 can be expressed as product of two numbers in the following ways:
1 * 256
2 * 128
4 * 64
8 * 32
16 * 16
The sum of the roots is maximum when the roots are 1 and 256 and the maximum sum is 1 + 256 = 257.
The least value possible for b is therefore -257.
Answer " E
I know this is rather a simple question but i am having trouble understanding the basic concepts. Can someone please elaborate??
Hi,
let me try to explain it to you..
y = x^2 + bx + 256..
when we say the curve cuts the x-axis at (h,0) and (k,0), it means h and k are the roots of equation since here y is 0
x^2 + bx + 256 = 0...
We can see both (h,0) and (k,0) have y as 0, which converts the equation y = x^2 + bx + 256.. as x^2 + bx + 256 = 0...
for a quadratic equation, ax^2+bx+c=0, the product of its roots are c/a and sum= -b/a..
here a=1, b=b and c=256
so here product= hk=c=256..
sum= -b =h+k
sice we are looking for the max sum, so as to have least b, we take h and k as 256 and 1..
P=256*1=256
so SUM = -b= 256+1=257
so b=-257
Thank you so much. This is extremely helpful