Sagot :
[tex] x^{2} - 25 = 0 \\ x^{2} = 0 + 25 \\ x^{2} = 25 \\ x = \pm \sqrt{25} \\ \boxed{x = \pm 5}[/tex]
correct alternatives : C , D
correct alternatives : C , D
x² - 25 = 0
The left side is the difference of 2 squares,
so we know right away, without any uncertainty
or sweat, that it can be written as
(x + 5) (x - 5) ,
and we know that it's equal to zero when either factor is zero.
Now let's look at the choices:
A. X = -1 Not a chance.
B. X = -3 Also no.
C. X = -5 Yes that's good; that would make the first factor zero.
D. X = 5 Yes that's good too; it would make the second factor zero.
E. X = 3 Not true. Don't know how they came up with it.
F. X = 1 Equally not true.
The left side is the difference of 2 squares,
so we know right away, without any uncertainty
or sweat, that it can be written as
(x + 5) (x - 5) ,
and we know that it's equal to zero when either factor is zero.
Now let's look at the choices:
A. X = -1 Not a chance.
B. X = -3 Also no.
C. X = -5 Yes that's good; that would make the first factor zero.
D. X = 5 Yes that's good too; it would make the second factor zero.
E. X = 3 Not true. Don't know how they came up with it.
F. X = 1 Equally not true.