帮人问三道英文数学题···分不多了,（1）IfPvariesinverselyasthesquareofT,andP=6whenT=-3,thenwhatisthevalueoftheconstantofproportionalityinthiscase?WhatformuladescribestherelationshipbetweenPand（2）

Question

帮人问三道英文数学题···分不多了,
（1）If P varies inversely as the square of T,and P = 6 when T = -3,then what is the value of the constant of
proportionality in this case?What formula describes the relationship between P and
（2）Q varies directly as the cube of X,and Q = -4 when X = 3.
What will be the value of Q when X =
（3）If z = kxy ,where k is a constant,then we say that “z varies jointly as x and y”.
The force of gravity (the force of the gravitational attraction between two bodies) varies jointly as the masses of
the two bodies and inversely as the square of the distance between them.
Let 1 M and 2 M be the masses of the two bodies,let R represent the distance between the two bodies and let
g F represent for force of gravity.
Express the relationship between 1 M ,2 M ,R and g F symbolically.

Answer 1

(1)如果P与T的平方成反比,且当T=-3时,P=6,那么此时的比例系数是多少?关于P和T的表达式是什么?
设比例系数为k.
因为 P与T的平方成反比,
所以 P=k/(T^2).
而 当T=-3时,P=6,
所以 6=k/9,
解得 k=54.
所以 比例系数为54 ,P=54/(T^2).
(2)Q与X的立方成正比,且当X=3时,Q=-4.当X=5时,Q的值是多少?
因为 Q与X的立方成正比,
所以 存在比例系数k,使得
Q=kX^3.
而 当X=3时,Q=-4,
所以 -4=27k,
解得 k= -4/27.
所以 当X=5时,
Q= -(4/27)*5^3= -500/27.
上面两题想办法翻译回去就行了.不知对不对.
vary directly as :成正比.
vary inversely as :成反比.