The area of a right angled trapezoid with a height of 4 decimeters is 68 square decimeters. If the upper bottom is increased by 6 decimeters, it will become a rectangle, then the lower bottom of the trapezoid is 68 square decimeters______ Decimeter

The area of a right angled trapezoid with a height of 4 decimeters is 68 square decimeters. If the upper bottom is increased by 6 decimeters, it will become a rectangle, then the lower bottom of the trapezoid is 68 square decimeters______ Decimeter

The sum of trapezoidal bottom is: 68 × 2 △ 4 = 34 (decimeter), the length of trapezoidal bottom is: (34 + 6) △ 2 = 20 (decimeter), answer: the length of trapezoidal bottom is 20 decimeter

A right triangle, the bottom is 56 decimeters, if the bottom increases 35 decimeters, the right trapezoid will become a square, find the area of the right trapezoid

(56+56-35)*56/2=2156(dm^2)

There are 20 girls in a class and 5 / 9 boys in the class. How many students are there in the class?

Let the total number of students be X. 20 + 5 / 9x = X. solve the equation to get x = 45. So there are 45 students in the class

What's one in six times seven

-7/6

If the limit of a sequence is greater than zero, then are all the items of the sequence greater than zero? Please analyze the reasons and give some examples!

Piecewise function is better than scalar function
Limit refers to the trend of sequence when n tends to infinity
So the preceding finite terms can all be less than zero

Xiaodong's mother received 480 yuan of bonus from her unit, including 86 pieces of 2 yuan, 5 yuan and 10 yuan, and the number of 5 yuan and 10 yuan is equal. How many of these three kinds of RMB?

If there are x sheets of 5 yuan and X sheets of 10 yuan, there are (86-2x) sheets of 2 yuan, (86-2x) × 2 + 10x + 5x = 480, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 172-4x + 15x = 480, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp

1,1,3,7,17,41,()

, 1,3,7,17,41, (99) the first plus the second multiplied by 2 equals the third number. By analogy, 1 + 1 * 2 = 3 1 + 3 * 2 = 7 3 + 7 * 2 = 17 7 + 17 * 2 = 41 17 + 41 * 2 = 99“

Given that a, B and C are positive real numbers, a ^ 2 + B ^ 2 = C ^ 2, when n is a natural number greater than 2, compare the size of C ^ n and a ^ n + B ^ n

Because a ^ 2 + B ^ 2 = C ^ 2, there is an acute angle t such that a = C * cost, B = C * Sint
a^n+b^n
=c^n*(cost)^n+c^n*(sint)^n
=C ^ n [(cost) ^ n + (Sint) ^ n] (because 0

Derivative of y = sin ^ NX * cosnx
nothing

y'={[(sinx)^n][(cosx)^n]}'
=ncosx(sinx)^(n-1)-nsinx(cosx)^(n-1)

As soon as the sun shines, () becomes air. When it rises to the sky, it becomes countless (), connecting (), in the air (). Sometimes I wear (), sometimes I wear (), () and (). I put my red robe on (). People call me ()

As soon as the sun shines, (water) becomes air. When it rises to the sky, it becomes innumerable (tiny) dots, connecting (one piece), floating (floating) in the air. Sometimes I wear (white clothes), sometimes I wear (black clothes), (morning) and (evening) I put my red robe on (body). People call me ("cloud")