solve (x+4)(x-5) = 0# Faculty - 发考题
A*e
1 楼
I am proctoring an exam now. When making the exam, I was trying to simplify
the calculations rather focusing on the conceptual understanding. So, one
of the questions has such a step - solve (x+4)(x-5) = 0. I just saw a
student spent a quite long time to do this :
(x+4)(x-5) = x^2-5x+4x -20 = x^2-x-20 = 0, then x = (1+/-sqrt(1-4*(-20)))/2
= -4 and 5.
This is actually not bad. Very frequently I see some silly mistakes like
exp(-t) + exp(-4t) = exp(-5t). Should I laugh or feel sad? When I first
started teaching years ago, I often felt frustrated and sometimes got upset
with students. Now, I just try to have fun from it, otherwise it is too
much pain.
the calculations rather focusing on the conceptual understanding. So, one
of the questions has such a step - solve (x+4)(x-5) = 0. I just saw a
student spent a quite long time to do this :
(x+4)(x-5) = x^2-5x+4x -20 = x^2-x-20 = 0, then x = (1+/-sqrt(1-4*(-20)))/2
= -4 and 5.
This is actually not bad. Very frequently I see some silly mistakes like
exp(-t) + exp(-4t) = exp(-5t). Should I laugh or feel sad? When I first
started teaching years ago, I often felt frustrated and sometimes got upset
with students. Now, I just try to have fun from it, otherwise it is too
much pain.
