First we use product rule
y=x^2lnx
dy/dx = x^2 d/dx (lnx) + lnx d/dx (x^2)
dy/dx = x^2 (1/x) + lnx (2x)
dy/dx = x + 2xlnx
now taking second derivative:
d2y/dx2 = 1 + 2[x (1/x) + lnx (1)]
d2y/dx2 = 1 + 2[1+lnx]
1+2+2lnx
3+2lnx is the answer
Check the picture below.
for "b", well, recall that the sum of all interior angles in a triangle is 180°.
for "a", "c" and "d", well, all those are just <u>intercepted arcs</u>.
1 mile=5280 feet
4 miles=21120 feet
21120×20÷100=4224. As a result, 20% of 4 miles is 4224 feet. Hope it help!
3x92 = 276 (first 3 exams)
average of at least 90 (90 x 4 = 360)
360 - 276 = 84
Answer
<span>she needs to score at least 84 on the fourth exam </span><span>in order to guarantee a final average of at least 90</span>
