Question

if the root of equation y^2+ky+15=0 is -3 & -5 ,then find the value of k
​

Answer 1

Answer:

Step-by-step explanation:

1 Subtract {y}^{2}y

​2

​​  from both sides.

ky+15=-{y}^{2}ky+15=−y

​2

​​  

2 Subtract 1515 from both sides.

ky=-{y}^{2}-15ky=−y

​2

​​ −15

3 Divide both sides by yy.

k=\frac{-{y}^{2}-15}{y}k=

​y

​

​−y

​2

​​ −15

​​  

4 Simplify  \frac{-{y}^{2}-15}{y}

​y

​

​−y

​2

​​ −15

​​   to  -y-\frac{15}{y}−y−

​y

​

​15

​​ .

k=-y-\frac{15}{y}k=−y−

​y

​

​15

​​  

Answer 2

Answer:

8

Step-by-step explanation:

here $y^{2}$+ky+15 = 0

& its roots are -3 & -5 it will satisfy the equation

so $(-3)^{2}+ k(-3)+15=0$

     => $9-3k=-15$

    $=> -3k=-24$

    $=> k = -24/-3 = 8$

put k = 8 & y=-5 & see if it satisfy ur ans is correct