下列数组中,不是勾股数组的是 ( )
A:8,12,15
B:7,25,24
C:5,12,13
D:3k,4k,5k(k为正整数)
⑴Lily is on the phone. ____ A.
⑵Jim can carry this bag.____ B.
⑶Be careful!The water is very hot.____ C.
⑷The apples are falling! ____ D.
⑸The plane is flying away.____ E.
若a,b∈R,ab>0,则 a4+4b4+1ab 的最小值为____.
赵强同学借了一本书,共280页,要在两周借期内读完,当他读了一半时,发现平时每天要多读21页才能在借期内读完.他读了前一半时,平均每天读多少页?如果设读前一半时,平均每天读x页,则下列方程中,正确的是( )