Solve for x x squared plus 4x minus 21 equals 0

x = -7 and x = 3

Step-by-step explanation:

x² + 4x - 21 = 0 factors as follows:  (x + 7)(x - 3) = 0.

Then x = -7 and x = 3.

Step-by-step explanation:

We have the following quadratic equation

To solve the equation we must factor it.

To factor the equation we must find 2 numbers b and c that when adding them, you obtain as result 4 () and when multiplying them, you obtain as result -21 ().

Then the polynomial will be factored in the following way:

You can verify that the numbers that meet this condition are:

So

Finally the solutions are:

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.

what is the original number? you forgot to add it.