Factor using quadratic formula: 2x^2-2x-40

Question

please explain the steps

Answer 1

okay,,,,,,

per previous answers,,,,by setting f(x)=0

x_r1=5 and x_r2=-4.and a=2

meaning f(x)=2x²-2x-40=2(x-5)(x-(-4)

f(x)=2x²-2x-40=2(x-5)(x+4)

check x=101

101²=(100+1)²=10,201

f(101)=2(101)²-2(101)-40=40,402-202-40=20,160

also.

f(101)=2(101-5)(101+4)=2(96)(105)=20,160

the expressions f)(x)=a(x-x_r1)(x-x_r2)

and f(x)=ax²+bx+c where b/a=-(x_r1+x_r2) and c/a=(x_r1)(x_r2)

are same (equivalent for any x)

Answer 2

Hi Alia

For

2x² - 2x -40

First you identify and line up the coefficients according to to the Quadratic Equation

f(x) = y = 0 = ax² + bx + c

You are given 2x² - 2x - 40

Then you plug the coefficients directly into the Quadratic Formula

x = (-b±SQRT(b²-4ac))/2a

Can you line up the coefficients

a =

b =

c =

Then just plug them into the Quadratic Formula above

You can and should look up both the Quadratic Equation, the Quadratic Formula and they’re associated coefficients in your text and online.

For the actual factoring once you obtain the x intercepts, or zeroes, you can plug those into the factored format of the Quadratic Equation

a(x - r₁)(x - r₂) = 0

I hope this helps.

Answer 3

The quadratic formula is x = -b +/- sq root of (b²-4ac) divided by 2a

For this, a = 2, b = -2, c = -40

Plug them in.

x = 2 +/- sq. Root of (4-4(2)(-40)) divided by 4

x = 2 +/- sq. Root of 324 divided by 4

x = 2 +/- 18 divided by 4

2 + 18 = 20

20/4 is 5

That’s your first answer

2 - 18 = -16

-16/4 is -4

That’s your second answer

In short, the answer is x = -4 and 5