The height requirement of a desk is 100 m3 (unit: cm)

The height requirement of a desk is 100 m3 (unit: cm)

Indicates that the height of a desk should be between 97cm and 103cm

Find the tangent equation of curve y = - 1 / 2x & # 178; + 1 passing through point (2,47 / 2)

y‘=-x
Substituting x = 2 into the derivative gives k = - 2
∴y-47/2=-2（x-2）
y=-2x+51

A batch of goods can be transported by car 18 or 4 times at a time___ If the goods weigh 116 tons, they have already been shipped away___ Tons

2x-1/x+1+3x+1/x+2-5x-11/x-1=

（2x-1）（x+2）（x-1）+（3x+1）（x+1）（x-1）-（5x-11）（x+1）（x+2）
=2x²-31x-21

A and B two barrels of oil weigh 90 kg in total. After pouring 1 / 4 of a into B barrel, the weight ratio of a and B is 1:2. How much is a and B

At present, the number of barrels a accounts for 30% of the total
1/2÷（1＋1/2）＝1/3
Now there's a barrel
90 × 1 / 3 = 30 kg
It turns out that the nail barrel has
30 (1-25%) = 40 kg
It turns out that B barrel has
90-40 = 50 kg

Given the function y = (M + 1.5) x | 3 + 2m |, when m is the value, this function is a linear function, and the image passes through the second, third and fourth quadrants

Because the image passes through the second, third and fourth quadrants, the slope of the straight line is negative, that is, K

There are 30 boys and 25 girls in a class. What is the ratio of girls to boys? How many more boys than girls?

The ratio of girls to boys is 25:30, that is 5:6. Boys are 30-25 / 25 = 5 / 25 = 1 / 5 more than girls

If a (A-1) - (A & sup2; + b) = 5, find the value of (a-b) & sup2 / 4 + ab

a(a—1）—（a²＋b)＝—5a²—a—a²—b＝—5—a—b＝—5a＋b=5（a—b)²/4＋ab=[（a—b)²＋4ab]/4=[a²—2ab＋b²＋4ab]/4=[a²＋2ab＋b²]/4=(a＋b)²/4=5²/4=25/...

Girls account for 2 / 5 of the total number in the chorus. Later, five girls were replaced by five boys. At this time, the ratio of girls to boys is 3:7. How many boys and girls are there

There are x girls, y boys and X-Y girls
Equation:
Y/X=2/5
(Y-5)/(X-Y+5)=3/7
Solution
X=50
Y=20
So there are 30 boys and 20 girls

Let the quadratic equation (3 + LGM) x ^ 2 + 2 (1 + LGM) x + 1 = 0 have two unequal real roots, and find the value of M

There are two unequal real roots, so the quadratic coefficient is not 0, the discriminant is greater than 03 + LGM ≠ 0, LGM ≠ - 3M is not equal to 1 / 1000, the discriminant △ > 0, so 4 (1 + LGM) & sup2; - 4 (3 + LGM) > 0lg & sup2; m + 2lgm + 1 - LGM - 3 > 0lg & sup2; m + LGM - 2 > 0