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x^2-49=0 solve using quadratic formula

x^2-49=0 I know the answer is 7,-7 but I am not able to get that. please show me the steps so I can see what I am missing thank you

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Philip P. | Effective and Affordable Math TutorEffective and Affordable Math Tutor
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x^2-49=0 I know the answer is 7,-7 but I am not able to get that. please show me the steps so I can see what I am missing thank you
 
x2 - 49 = 0
 
Easiest solution:
 
x2 = 49                 [Add 49 to both sides]
 
√x2 = √49            [Take the square root of both sides]
 
x = ±7
 
Using quadratic formula:
 
-(b/2a)±[b2-4ac]1/2/2a    [for ax2+bx+c=0]
 
Your equation is (1)x2 + (0)x + (-49) = 0
 
so a=1, b=0, c=-49.  Plugging them into the quadratic formula:
 
-(0/2)±[02-4(1)(-49)]1/2/2
 
0 ± [4*49]1/2/2
 
± (2*7)/2
 
x = ±7