若将(2x)n-81分解成(4x2+9)(2x+3)(2x-3),则n的值是[]
A.2B.4C.6D.8
A.2B.4C.6D.8
若两个非零数的和是零,则它们的商是()
A.0B.1C.-1D.以上结论都不对
A.0B.1C.-1D.以上结论都不对
分解因式:(a+2)(a-2)+3a=.
(3xy)2?(-15x6y5z)÷(-115x5y6)=()
A.9x3yzB.27x2yzC.27x3yzD.27x3z
A.9x3yzB.27x2yzC.27x3yzD.27x3z
一只小狗的奔跑速度为a千米/时,从A地到B地的路程为(b+15)千米,则这只小狗从A地到B地所用的时间为______h;当a=21,b=12时,它所用的时间为______h.
减去-3m等于5m2-3m-5的式子是[]
A.5(m2-1)B.5m2-6m-5C.5(m2+1)D.-(5m2+6m-5)
A.5(m2-1)B.5m2-6m-5C.5(m2+1)D.-(5m2+6m-5)
若am=2,an=4,则am+n=()。
(9分)小王买了50元的乘车月票卡,如果小王乘车的次数用n表示,则记录他每次乘车后的余额m(元)如下表:次数余额m(元)150-0.8250-1.6350-2.4450-3.2……(1)写出用乘车的次数n表示余额m的式子。(2)利用上式计算乘了13次车后,余额为多少?(3)小王最多能乘几次车?
计算(a+3)(a2+9)(a﹣3).
毕业班几个同学合影留念,要交底板费2元,加洗2张收0.5元.每位参加照相的同学均加洗1张,另外再加洗2张送给班主任和数学老师留念,预计每人平均出钱不超过1元.问参加照相的同学至少有几位?
人类的遗传物质就是DNA,人类的DNA是很长的链,最短的22号染色体也长达30000000个核苷酸,30000000用科学记数法表示为个[]
A.3×108B.3×107C.3×106D.0.3×108
A.3×108B.3×107C.3×106D.0.3×108
28. The young black people used their ______to dance at that time.
A. legsB. headsC. arms and shouldersD. A,B and C
A. legsB. headsC. arms and shouldersD. A,B and C
He left secretly and everyone thought his d______ was very strange.
To Miss Bean the most important thing for a student is to ________.
A. pay close attention to what the teacher saysB. learn to think and have one’s own ideaC. keep silent and unnoticed in classD. get special attention from the teacher
A. pay close attention to what the teacher saysB. learn to think and have one’s own ideaC. keep silent and unnoticed in classD. get special attention from the teacher
观察下列各个算式:1×3+1=4=22;2×4+1=9=32;3×5+1=16=42;4×6+1=25=52;根据上面的规律,请你用一个含n(n>0的整数)的等式将上面的规律表示出来______.
(2011?陕西)我国第六次人口普查显示,全国人口为1370536875人,将这个总人口数(保留三个有效数字)用科学记数法表示为()
A.1.37×109B.1.37×107C.1.37×108D.1.37×1010
A.1.37×109B.1.37×107C.1.37×108D.1.37×1010
This computer centre islarger thanthat one in the area.
A.one sixthB.four ninthsC.fifth fourD.two third
A.one sixthB.four ninthsC.fifth fourD.two third
k=______时,代数式k+13的值比3k+12的值小1?
一个数加-3.6,和为-0.36,那么这个数是()
A.-2.24B.-3.96C.3.24D.3.96
A.-2.24B.-3.96C.3.24D.3.96
是被子植物起源单元说的主要代表人物。①恩格勒②哈钦松③胡先辅④塔赫他间⑤克朗奎斯特
A.①②③B.①②④C.②③④D.②④⑤
A.①②③B.①②④C.②③④D.②④⑤