Question

If -2 is a root of the quadratic equation x²-5x+c find the value of c

Answer 1

Explanation:

P(x)= x^2-5x+c=0

P (-2)= (-2)^2-5 (-2)+c=0

= 4+10+c=0

=14+c=0

C=(-14)

Answer 2

`\fbox{\begin{minipage}{4em}c = -14\end{minipage}}`

Explanation:

Given:

A quadratic equation:
`x^(2) - 5x + c = 0`, with
`x =-2` is a solution.

Solve for:

Value of c

Step 1: define the problem

If
`x = -2` is a solution of equation
`f(x) = 0`, then
`f(-2) = 0`

Step 2: Perform the calculation

Substitute
`x = -2` into original quadratic equation, we have:

`(-2)^(2) - 5(-2) + c = 0`

Perform the square and multiplication:

`4 + 10 + c = 0`

Transfer all of numbers to the right side, except c:

(notice for the change in sign of numbers)

`c = (-4) + (-10)`

Perform the sum on the right side to get c:

`c = -14`

Hope this helps!

:)