Melody

x= -3 -x^2+6x-4 

\(x= -3 -x^2+6x-4 \\ 0= -3 -x^2+5x-4 \\ 0= -x^2+5x-7 \\ 0= x^2-5x+7 \\ \triangle=b^2-4ac=25-28=-3\\ since\;\;\triangle<0\;\;\text{there are no real solutions}\\~\\ \text{Note that the triangle is called the discriminant} \)

Confused about scientific notation ie. 4.28x10^28x1/6.2x10^29x6x20.001

\(4.28*10^{28}*\frac{1}{6.2}*10^{29}*6*20.001\\ =\frac{4.28*1*6*20.001}{6.2}*10^{29}*10^{28}\\ =\frac{4.28*6*20.001}{6.2}*10^{57}\\ =\frac{4.28*6*20.001}{6.2}*10^{57}\\ \approx 82.84285161*10^{57}\\ \approx 8.284285161*10*10^{57}\\ \approx 8.284285161*10^{58}\\\)

what is n/7=47r3? help me i have to submit it tomorrow.

I'll do a different one and you can copy the method   

q/5=19r2

\(\frac{t}{5}=19r2\\ \frac{t}{5}=19\frac{2}{5}\\ \frac{t}{5}=\frac{5*19+2}{5}\\ \frac{t}{5}=\frac{97}{5}\\ t=97 \)

When john left he had 120 cards :)

To go from the third last line to the second last line is just dividing both sides by the same thing.

Have I misunderstood your question?

It'll be 1- P (exactly 0,1 or 2 correct)

P(0)=0.8^6

P(1)=6C1×0.2×0.8^5

P (2)=6C2×0.2^2×0.8^4

Add those together and subtract the answer from 1.

sec(-11pi/2)

I'll do it on the web2 calc and see what happens.....

sec(-11pi/2) = 1.047261908623317

Yes the is the web2 answer but it is NOT correct.  

https://www.wolframalpha.com/input/?i=sec(-11pi%2F2)

I'll message the owner of the site and see it he can fix or explain it.

sec(-11pi/2)

\(sec(\frac{-11\pi}{2})\\ =sec(\frac{-12\pi}{2}+\frac{\pi}{2})\\ =sec(\frac{\pi}{2})\\ =\frac{1}{cos(90^\circ)}\\ =\frac{1}{0}\\ =undefined\)