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MArishka [77]
3 years ago
10

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

Mathematics
2 answers:
iren2701 [21]3 years ago
7 0

Answer:

x = 3\\x = -7

Step-by-step explanation:

We have the following quadratic equation

x^2 + 4x - 21 =0

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 (c + b = 4) and when multiplying them, you obtain as result -21 (c * b = -21).

Then the polynomial will be factored in the following way:

(x+c)(x + b) = 0

You can verify that the numbers that meet this condition are:b = 7\\c = -3

So

x^2 + 4x - 21 =(x-3)(x + 7)=0

Finally the solutions are:

x = 3\\x = -7

suter [353]3 years ago
3 0

Answer:

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.

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