Daiana L.

asked • 03/06/19

How do I solve x² + 2x − 8 = 0?

Eric W.

(x+4)*(x-2)=0, then X=-4 AND X=2.
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09/05/19

PAT T.

when the variable is to the 2nd power you have a quadratic equation. The standard form ax^2 + bx + c where a is not equal to zero. to solve using the formula : x = -b + or - the square root of (b^2 - 4*a*c) all over 2*a here you have a=1, b=2 and c = -8 substitute the values in the formula and simplify. you should get the same answer as above. When a = 1 it is faster to solve by factoring but the formula works for any quadratic.
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05/31/20

Vivek A.

The equation of finding X= Square root of (b^2 +or- 4*a*c), Here b=2, a=a and c=-8. And also you can use (x+4)*(x-2)=0,
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08/18/20

San P.

Ok I'll respond way simpler than any of the experts you hear. They are right, just not easy. Theres a really easy way to know this. x^2 is always going to be A x is always going to be B And any plain number will always be C So just plug it into the Quadratic formula { (-b±√(b^2-4ac))/2a } The ± means plus or minus so you have to do this equation 2x one with + and one with -. Solve it and you get {-4, 2} in Set Builder Notation as x is equal to 2 things. None of these Experts know it the easy way lol.
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05/12/21

Mohammad U.

There are more possible ways to do it, without using quadratic formula I will do it in a simplest way, multiply X^2 with -8 in a rough work(RW), which will be -8x^2, now find the possible ways by multiplying it should give -8x^2, and by adding or subtracting it give 2x, and like 1*8, 2*4, look there are more possible ways, but have to pick that one which satisfies our requirement, we will pick 2*4. The equation will become like this: (x^2)+4x-2x-8=0 now check whether it is satisfying the conditions or not, like by the terms in the middle by multiplying it is giving -8x^2, and by adding +2x, yes it is satisfying the terms. now taking commons from right 2 and left 2 terms, x(x+4)-2(x+4)=0 taking x+4 common, the equation will become: (x+4)(x-2)=0 now taking x+4=0 and x-2=0 so it becomes: x= -4 AND x=2 S.S= {-4,2}
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10/27/21

2 Answers By Expert Tutors

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Eric H. answered • 02/12/21

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When an equation has a squared term in it such as x2 + 2x - 8 = 0, it's called a polynomial equation.


The rule for solving a polynomial equation is to first set it equal to 0, then factor.


Since this equation is already set equal to 0, our first step is to factor the left side.


To factor x2 + 2x - 8, we need the factors of -8 that add to +2, which are +4 and -2.


So we have (x + 4)(x - 2) = 0.


Whenever two terms are multiplied together to equal 0,

this means that either one or the other must equal 0.


So if (x + 4)(x - 2) = 0, then either x + 4 = 0 or x - 2 = 0.


Solving each equation from here, we subtract 4 from both sides of our first equation

to get x = -4 and we add 2 to both sides of our second equation to get x = 2.


So this equation has two solutions, -4 and 2, and we can put our answer in set notation as {-4, 2}.

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