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PSAT 1.7 Math Diagnostic. What is the value of x?
More Video DetailsTranscript
- 00:00
Thank you We sneak and here's your shmoop du jour
- 00:05
brought to you by hot dogs We hope you'll relish
- 00:08
this one If four square root of ax equals eight
- 00:14
Acts minus 24 what's the value of acts and hear
- 00:17
potential answers all right little fashion algebra but what a
Full Transcript
- 00:21
mess It looks simple enough but once we realize that
- 00:24
there's a square root on one side not the other
- 00:27
and that multiplying or adding anything that both sides only
- 00:30
makes it look more daunting it's almost enough to make
- 00:32
us throw our hands up in the air give up
- 00:35
on this problem and distract ourselves instead with a hot
- 00:37
dog or two But then inspiration strikes You don't even
- 00:41
have to worry about simplifying this equation in a test
- 00:44
situation where every seconds precious why not go easy on
- 00:47
ourselves and take a shortcut here All we have to
- 00:49
do is plug in the four answer choices one by
- 00:52
one until we find the one that makes the equation
- 00:54
true It's quick it's easy and shortcuts go there's Very
- 00:57
little chance of us getting it wrong So we'll start
- 01:00
with a a and see if that works well Two
- 01:03
point two five Lugging that into the equation We get
- 01:05
four times square to two point two five equals eight
- 01:09
times two Point two five minutes twenty four we'll square
- 01:12
in a two point two five one point five times
- 01:14
for and that six on the right side of the
- 01:17
equation eight times two point two fives eighteen minutes twenty
- 01:21
for well that's negative six we don't see any absolute
- 01:24
value signs around that sucker so we could get rid
- 01:26
of a what about c five else plugging in this
- 01:30
time We've got four times square root of five which
- 01:33
can be simplified more than four square route five equals
- 01:37
eight times five or forty minus twenty four which is
- 01:40
sixteen One side still has square root symbol on the
- 01:43
other dozen Well in this scenario the equal signs a
- 01:46
big fat liar and ain't see let's try d eight
- 01:50
unfortunately that same problem here eight is the same as
- 01:52
four times too so we can rewrite it as two
- 01:55
square root of two But even still no matter how
- 01:58
you cut it we're gonna end up with a square
- 02:00
root symbol on the left side of the equation and
- 02:02
there won't be one on the right so will bid
- 02:04
and not so fond farewell to d well the right
- 02:07
answer is b for the square root of four is
- 02:09
exactly to which gets rid of that ugly symbol Two
- 02:12
times Four is eight equals eight tons for or thirty
- 02:15
two minus twenty four which is also ate and there's
- 02:17
our true statement Speaking of true statements if he ever
- 02:20
tried ordering a hot dog with ketchup in the city
- 02:22
of chicago you will immediately be arrested You don't believe 00:02:25.865 --> [endTime] us Just try it We double hot dog area
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