Don't leave your English books at home

Don't leave your English books at home

Don't put your English book at home

Xiaowen bought a math book and an extra-curricular book in the bookstore. It cost 76 yuan in total. It is known that the price ratio of the two books is 3:2, so the data book and the extra-curricular reading
How much is each item?

76 ÷ (3 + 2) = 15.2 yuan
Information book: 15.2 × 3 = 45.6 yuan
Extracurricular reading materials: 15.2 × 2 = 30.4 yuan

A parallelogram and a triangle have the same base and height. It is known that the area of a parallelogram is 45 square centimeters. What is the area of a triangle?
Don't understand = = emergency heip!

If a parallelogram and a triangle have the same base and height, then the area of the triangle is half that of the parallelogram
So the area of the triangle is 45 / 2 = 22.5 square centimeters

(√3+1)∧2013--2(√3+1)∧2012--2(√3+1)∧2011+2013

(√3+1)∧2013--2(√3+1)∧2012--2(√3+1)∧2011+2013
=(√3+1)^2011[(√3+1)²-2(√3+1)-2]+2013
=(√3+1)^2011(3+2√3+1-2√3-2-2)+2013
=(√3+1)^2010x0+2013
=2013

In the triangle ABC, ad is vertical to BC, the perpendicular foot is D, and ad = BC, find the maximum value of AB / AC + AC / ab

cosA=(b²+c²-a²)/2bc(b²+c²)/bc=2cosA+a²/bc…… （1）
SΔABC=bcsinA/2=a²/2 a²/bc=sinA …… （2）
(2) Substituting (1) to get:
b/c+c/b=（b²+c²)/bc=2cosA+sinA=√（1²+2²）sin（A+Q） （tanQ=2/1）
=√5sin（A+Q）
∵|sin（A+Q)|≤1
The maximum value of B / C + C / B is √ 5

Given the points a (1,0,1), B (4,4,6), C (2,2,3) and D (10,14,17), it is proved that a, B, C and D are in the same plane
Can it be: suppose a, B, C and D are in the same plane, then AB = x * AC + y * ad
Then AB = (3,4,5), AC = (1,2,2), ad = (9,14,16)
Then 3 = x + 9y
4=2X+14Y
5=2X+16Y
X = - 3 / 2
Y=1/2
So: ab = - 3 / 2Ac + 1 / 2ad
It is assumed that the four points a, B, C are in the same plane

Let ax + by + CZ + D = 0 be brought into point a (1,0,1), point B (4,4,6), point C (2,2,3), and a + C + D = 04A + 4B + 6C + D = 02A + 2B + 3C + D = 0, then a = 2B C = - 2b D = 02x + y-2z = 0 be brought into point d (10,14,17), 20 + 14-34 = 0, so a, B, C, D are coplanar

The area of a trapezoid is twice that of a triangle______ (judge right or wrong)

Because the top and bottom of the trapezoid are not equal, the areas of the two triangles are not equal, and the area of the trapezoid is not twice that of the triangle

What is the interval of the equation lgx = 3-x ^ 2?
In fact, it is a function zero point problem

Let's make sure that the square is x or (3-x)
For the former, Let f (x) = 3-x ^ 2-lgx
Then, f (1) = 2 > 0, f (radical 3) = - LG (radical 3) 0, f (radical 3)

As shown in the figure, lace of the same width is inlaid around a rectangular carpet. As shown in the figure, the rectangular pattern in the center of the carpet is 8m long and 6m wide, and the whole carpet area is 50.84m

Let the lace be x meters wide
（8+2x）（6+2x）=80
The solution is X1 = 1, X2 = - 8 (rounding)
Lace width 1m

Y = ax square + BX + C, when x = 1, y = - 4, when x = 2, y = - 3, when x equals 4, y = - 5, find ABC

x=1；y=-4；-4=a+b+c；
x=2；y=-3；-3=4a+2b+c；
x=4；y=-5；-5=16a+4b+c；
The results show that: a = - 2 / 3; b = 3; C = - 19 / 3;