Question

the entire graph of the equation
$y = x {}^ {2} + kx - x + 9$
is strictly above the x-axis then find the value of k​

Answer 1

Answer:

-5<k<7

Step-by-step explanation:

hey mate,

if the entire graph of the equation is above x-axis means that it doesn't cut x-axis at any point which implies that it has no real roots....

so,D<0

=>b²-4ac<0

=>(k-1)²-4*1*9<0

=>(k-7)(k+5)<0

=>k € (-5,7)