100 students had some homework. The following frequency tree shows which children and boys and girls and who did their homework. One of the girls is chosen at random. Work out the probability that this girl did not do her homework.

Find the gradient of f(x,y,z)equals=left parenthesis x squared plus y squared plus z squared right parenthesis superscript negative 1 divided by 2 baseline plus ln left parenthesis x right parenthesis x2+y2+z2−1/2+ln(xyz) at the point left parenthesis negative 2 comma 1 comma negative 2 right parenthesis(−2,1,−2).

Find the roots of the equation below. x^2 - 6 + 9 = 0

Simplify. (-2)^-3 a. -8 b. -1/8 c. 1/8 d. 8