Question

7 and -3 are the root of the Quadratic equation x^2+kx-21=0. What is the value of k

Answer 1

Answer:

In equation $x^{2} +kx-21 =0$, if 7 and -3 are roots of the given equation, then the value of k is -4

Step-by-step explanation:

Given

Roots of the equation = 7 and -3

Given

$x^{2} +kx-21 =0$

Let us substitute x with 7

That is,

$7^{2} +7k-21 = 0\\\\49+7k-21=0\\\\28 +7k = 0\\\\7k = -28\\\\k = \frac{-28}{7} \\\\k =-4$

So the value of k is -4