How to solve 7 x 2 = - 21 ?

Question

How to solve       7          x      2        =    -    21  ?

Corey Wise · Accepted Answer

First, divide each side of the equation by

7

to isolate the

x^{2}

term while keeping the equation balanced:

\frac{7 x^{2}}{7} = - \frac{21}{7}

\frac{7 x^{2}}{7} = - 3

x^{2} = - 3

To solve for

x

while keeping the equation balanced, we would then take the square root of either side of the equation.
However, there is no Real solution for the square root of a negative number, in this case the

\sqrt{- 3}

Hence, there is no real solution or the solution set is the empty or null set:

{\emptyset}

Norah Terrell · Accepted Answer

Divide       7   to both sides;                              7          7                            x      2        =    -          21      7                  x      2        =    -    3                                x          2                      =                  -        3             (Apply the square root property)      x    =    ±                  -        3            Since the radical&#039;s radical number is negative, there are no &quot;real solutions,&quot; but there are two &quot;complicated&quot; solutions:The above phrase can be rewritten as follows:      x    =                  -        1              ⋅          3        ,    x    =    -                  -        1              ⋅          3      *Recall that             -        1    =    i  Consequently, we can condense the expression to:Final answer therefore:       x    =    i          3        ,    x    =    -    i          3

How to solve 7x^2=-21?

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