Question

Please help I will give brainliest if two people answer my question

Answer 1

Answer:

Option 1. $0.25x^2+0.8x-8=0$ and 4. $-2x^2+5x=7$ would be solved by the quadratic formula.

Step-by-step explanation:

We know the quadratic formula is used to find the roots of the equation, $ax^{2}+bx+c=0$.

Now, according to the options, we see that all four options are quadratic equations.

But, we will not use the quadratic formula for all.

Because,

$-(x-3)(x+9)=0$ can be easily solved by substituting each individual factor to 0.

$3x^2=9$ also can be easily solve by dividing both sides by 3 and taking square root.

Thus, the only options which will require to the quadratic formula are,

$0.25x^2+0.8x-8=0$

$-2x^2+5x=7$

Hence, option 1 and 4 would be solved by the quadratic formula.

Answer 2

Hey there,

Well, we would have to remember that the quadratic formula.

For $ax^{2} +bx+c=0$

$x \frac{-b+ \sqrt{ b^{2}-4ac } }{2a}$

So by clarifying this formula, we would understand alot more on
how to answer this question.

Your correct answer would be: . . .

0.25x2+0.8x−8=0

And I believe it would also be 

−2x2+5x=7

Because they each illustrate the steps of the formula.

Hope this helps.

~Jurgen