10 Hardest Math Questions on the Digital SAT (DSAT Math Prep)

[@imarex2643]

After a week of learning desmos, I understood that it is a life saver in most of cases

[@mellaza]

14:40 you can plug in the numbers into a table, use y1~ax^21+bx1+c1 which will give you -2108 as c1, and subtract 4 which gives you -2112

[@sridurgarevu]

For question 8 with the linear table, there is a very easy way to work it out. 1) Create a table in Desmos and plug in the points 2) Type y1 ~ mx1 + b and it will give you the values of m and b which are equivalent to a and b in the problem. 3) Next just do a-b (m-b) and it will give you the answer 192.

[@rabiaaamir8311]

how do you create a table in desmos?

[@brindha6008]

@@rabiaaamir8311 just type "table" into desmos and it'll create a table

[@helpyourself1844]

this the single best thing ive found in youtube comments ever.

[@ivyleaguementors]

Nice method, thanks for sharing!

[@OverclockingCowboy]

For the “a = c+d” question 6:00, there is no need to use DESMOS. The given equation is obviously in the form x^2 - (c+d)^2 = x^2 - a^2. The answer can be eyeballed as Choice C.

[@elf7197]

yeah it's obvious bro

[@leyla._.3257]

THIS MAN IS SO USEFUL! THANK YOU A LOT!!

[@malielanijoy]

For question 7 with the quadratic table and y=f(x)+4, you can solve it in desmos really quick. 1. Recreate the table in Desmos 2. On the next line, type the quadratic equation y_1~(ax_1)^2+bx_1+c (It's the quadratic equation but you just need to put in that 1 at the bottom) 3. Desmos will solve and give you all the values for each, and you can just find the value of c, which is the y-int. You get c=-2104 4. Then just subtract 4 to cancel out the 4 added in the question stem: so -2108-4=-2112 It let me solve this problem in a flash. Ofc, I think it's important to know how to solve it by hand, too, so you know how it works. Just when taking the test, you need speed, and these type of shortcuts really help.

[@muffy4671]

It should be "-2108" instead of "-2104" in your comment, otherwise it's good

[@malielanijoy]

@muffy4671 oh, haha, thanks! I guess I was typing so fast I accidentally typed an extra 4. Thanks for letting me know! I'll fix that right away.

[@muffy4671]

@@malielanijoy no problem, good luck on your test!

[@malielanijoy]

@@muffy4671 thanks! You too! I'm taking it in December

[@muffy4671]

@@malielanijoy Hopefully me too, hope you get the score you want

[@Chaniesvlog7]

In question 7, 17:42 Why do we need to subtract 4 when it is f(x) +4. Don’t we need to add?

[@LC95297]

(23;8)is the vertex.. of f(x)+4. So the vertex of f(x) is (23;4) and then f(0) is -4(-23)²+4= -2112.

[@AbdulSubhan-p3j]

you solved question 3 with a quite difficult method its is a very very easy one

[@BackRankHero]

Definitely not me reading f(-9) = f(3) as f(-9) = 3. Lol spent quite some time scratching my head on that one, silly me

[@a.meforyou]

I tried to figure how to put that into Desmos as well 😅

[@gabrielanowicka9102]

this is so good, thank you so much!!

[@s0phadays]

at part 16:48 when we’re finding the vertex of the equation, why wasn’t the y coordinate “-8” instead of “8”. since the two points before had a y of -8? really confused

[@nitishmedi1711]

he took another 21,-8 for solving

[@YasminaMuzaffarova]

You're the best thanks a bunch

[@AyxanBaxışov-h3v]

12:23 you choose the y 0 But they give k

[@2o3529]

k represents the y value of the vertex, and since a > 0 (2/3), there'll be y values above k that exist in the parabola because it opens upwards infinitely

[@GuywholikesCats1]

love the john green reference!

[@ivyleaguementors]

guilty as charged. big crash course fan over here

[@jwmathtutoring]

Q2 & Q5 & Q7 & Q8 can both be done entirely in Desmos in ~20 secs. Also, Q3 is not one of the 10 hardest DSAT Math questions. Probably not even in the top 50 to be honest.

[@kathrinewells9072]

Thank you. Soooooooo much!!!

[@elf7197]

my note: 9:10 15:00 NEED to down shift

[@immopanda]

x^2- (c^2+2cd+d^2), c^2+2cd+d^2 = (c+d)^2 = a^2, x^2 - a^2, (x+a)(x-a)

[@mariamasri4551]

Finally someone like me !

[@skelly4522]

does anyone know why what he plugged into desmos for the last question doesn't match what the answer choices are? I'm having trouble understanding how he got answers when he plugged in points and when I tried I didnt

[@PujanShahiThakuri]

X and y values

[@colour9003]

why can it not be C in the last question? (0, 2.333 is also correct)

[@toyushi]

So helpful! Thank uuu

[@jayden7194]

Thank you

[@creedscorner]

For the vertex form problem, don’t you need to subtract four from all the terms since f(x) is y-4?

[@ivyleaguementors]

That's right. In this case, I just did that step at the end, but you could also do it earlier on.

[@PujanShahiThakuri]

​@ivyleaguementors how we do that

[@davidkosata3051]

cool, how much time do you have for these questions on the real test?

[@alepixys9907]

32mins for 22questions each module

[@leyla._.3257]

@@alepixys9907 it is almost 35 mins, not 32)

[@ivyleaguementors]

On each module of the math section, you'll have to answer 22 questions in 35 minutes. That's a little over a minute and a half per question. However, keep in mind that the easier questions can often be answered quickly, so you'll probably have more time than that for the hard questions like these.

[@ivyleaguementors]

That's right. 35 for math, 32 for reading & writing

[@jonathanmoges7566]

i think you implement desmos on many of this questions

[@maryamolaogun8800]

I barely know math and I was wondering if u can treat all the sat math questions to prepare me. PS Just a thought

[@ivyleaguementors]

Check out the official question bank. There are around 1000 math questions there along with answer explanations.

[@kiranpaudel5191]

thanks

[@tanner1376]

9:09

[@dagmadera5810]

I still believe that the answer for question number 9 is C. I cant understand why It is B

[@mellaza]

if you assume that a=-7 and b=5 like he does in the video, when you plug those numbers in for C, you get 14/5 as the slope, which is not the negative reciprocal of -10/7 and therefore not perpendicular

[@ivyleaguementors]

Yep, that's the right explanation

[@TirthShah-n5j]

D can also be a possible answer in last question

[@TheSatSlayers]

6/10 ugh

[@ivyleaguementors]

That's actually not bad considering that these are among the hardest questions out there, and you'd only get a couple of questions this hard on a real test.

[@akshajv6093]

I believe for #2 it should he b-12 not b-13

[@ivyleaguementors]

I think you're forgetting the first term in the equation. When we plug in that point, we get -75/7 = -a^0 + b - 12 Since a^0 will equal 1, no matter the value of a, this can be reduced to -(1) + b - 12, or b - 13 I hope that helps.

[@TesfayeTekle-h1r]

Not ax it is xsquare

[@VincentNguyen-ov4ox]

you talk like a preist

[@ivyleaguementors]

haha thanks

[@PujanShahiThakuri]

What's the c in 11:18 lol confusing