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OpenStudy (anonymous):
Solve for x: −4|x + 5| = −16
x = 21 over 4, x = −11 over 4
x = −1, x = 9
x = −1, x = −9
No solution
myininaya (myininaya):
Try dividing both sides first by the -4 to isolate the absolute value part
OpenStudy (anonymous):
1, and -4?
myininaya (myininaya):
no just divide both sides of the equation by -4
OpenStudy (anonymous):
ok
now what
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myininaya (myininaya):
what do you have after doing that?
OpenStudy (anonymous):
x: 1|x + 5| = 4
myininaya (myininaya):
we have |x+5|=4
myininaya (myininaya):
now |x+5| can equal x+5 or -(x+5)
OpenStudy (anonymous):
-1?
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myininaya (myininaya):
whenever you have |f(x)|, this can be f(x) or -[f(x)]
It all defends on values of x that make f positive or negative
myininaya (myininaya):
so since we have
|x+5| can be different things (you know depending on the value of x)
then that means we will have two equations to consider when solving
we have to consider
x+5=4 and -(x+5)=4
myininaya (myininaya):
i missed the word 2 above
|x+5| can be two different things which means we have two different equations to consider when solve |x+5|=4
so what do you get when you solve both x+5=4 and -(x+5)=4
OpenStudy (anonymous):
-1 + 5 = 4
myininaya (myininaya):
so are you saying one solution is -1?
since x+5=4 gives you x=4-5=-1
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OpenStudy (anonymous):
yes
myininaya (myininaya):
now what about the other solution?
-(x+5)=4
OpenStudy (anonymous):
-9
myininaya (myininaya):
right because -(x+5)=4 implies we have x+5=-4
which gives x=-4-5=-9