Question

In the polynomial below what number should replace the question mark to produce a difference of squares? x^2+?x-25

A.0
B.25
C.5
D.10

Answer 1

Hello from MrBillDoesMath!

Answer: A

Discussion:

An unusual question. Note that if "? = 0" then

x^2 + ?x - 25 = x^2 + 0 - 25 = x^2 - 25 = (x+5)(x-5)

Thank you,

MrB

Answer 2

? = 0

A is correct.

Explanation:

Given: Polynomial
`x^2+?x-25`

We need to make it difference of square.

It is quadratic form.

`y=ax^2+bx+c`

Difference of square:

`y=x^2-d^2`

For difference of square the x term can't be there.

Thus, The coefficient of x must be 0 for quadratic equation.

`ax^2+bx+c\rightarrow x^2-d^2`

coefficient of x must be 0

`x^2+?x-25\rightarrow x^2+0x-25`

`?\rightarrow 0`

Hence, The question marks replace by 0 to make equation perfect square.