Write the expression 2i^15-i^7 in the standard form a + bi

2-digit numbers less than 91 which are 1 less than a multiple of 10

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).

36 inches/second = yards/minute how many yards?