Question

How do you evaluate `7x ^ { 2} - 5x + 6- ( 12x ^ { 2} + 9x - 8)`?

Answer 1

See below.

Explanation:

When we see a minus sign by itself without a number in front of the bracket, we need to multiply each term in the bracket by `-1`.

`therefore`

`-1*12x^2=-12x^2`
`-1*9x=-9x`
`-1*-8=8`

This means our expression is now

`7x^2-5x+6-12x^2-9x+8`
Now we simplify by combining like terms (`x^2,x` and constants).

`therefore`

Final answer : `-5x^2-14x+14`

Answer 2

see a step process below;

Explanation:

`7x^2 - 5x + 6 -(12x^2 + 9x - 8)`

Open the bracket and simplify..

`7x^2 - 5x + 6 - 12x^2 - 9x + 8`

`7x^2 - 12x^2 - 5x - 9x + 6 + 8`

`-5x^2 - 14x + 12 -> "Quadratic Equation"`

Now solving the quadratic equation..

Using;

`x = (-b +- sqrt (b^2 - 4ac))/(2a)`

Where;

`a = -5`

`b = -14`

`c = 12`

Substituting the values..

`x = (-(-14) +- sqrt ((-14)^2 - 4(-5)(12)))/(2(-5)`

`x = (14 +- sqrt (196 + 240))/(-10)`

`x = (14 +- sqrt436)/(-10)`

Hope this helps!

Answer 3

see a step process below;

Explanation:

`7x^2 - 5x + 6 -(12x^2 + 9x - 8)`

Open the bracket and simplify..

`7x^2 - 5x + 6 - 12x^2 - 9x + 8`

`7x^2 - 12x^2 - 5x - 9x + 6 + 8`

`-5x^2 - 14x + 12 -> "Quadratic Equation"`

Now solving the quadratic equation..

Using;

`x = (-b +- sqrt (b^2 - 4ac))/(2a)`

Where;

`a = -5`

`b = -14`

`c = 12`

Substituting the values..

`x = (-(-14) +- sqrt ((-14)^2 - 4(-5)(12)))/(2(-5)`

`x = (14 +- sqrt (196 + 240))/(-10)`

`x = (14 +- sqrt436)/(-10)`

Hope this helps!