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( 1)- 1 (2)B
Two. Bistatic navigation
1-5 CCDAB
(6) 1; -6; 7 (7)k≤2 (8)①③ (9)3/4 ( 10)
(1 1) solution: suppose the price is reduced by x yuan.
(40-x)(20+2x)= 1200
The solution is x 1= 10 (truncation).
x2=20
In order to reduce inventory as soon as possible
A: Every shirt will be reduced in price, 20 yuan.
(12) Solution: ① The ∵ equation has two unequal real roots.
∴b? -4ac>0 ∴(-3)? -4(m- 1)>0
∴m< 13/4
② When the ∵ equation has two equal real roots.
b? -4ac=0 ∴(-3)? -4(m- 1)=0
∴m= 13/4
∴ One-variable quadratic equation is X? -3x+9/4=0
The root of the equation is x=3/2.
(13) solution: ① 10 times: P = 6/ 10 = 3/5; 0 = 3/5; 20 times: p =10/20 =1/2; 30 times: p =17/30; 40 times: P=23/40
②:P= 1/2
3 not necessarily.
(14) solution: let x? +2x=y ∴y? -7y-8=0
∴y 1=8 y2=- 1
When y=8, x? For +2x=8, X 1=2 x2=-4.
When y=- 1 For +2x=- 1, X=- 1
( 15)① 2x? +4x+3>0
2(x? +2x)>-3
2(x? +2x+ 1)>-3+2
2(x+ 1)? >- 1
(x+ 1)? >- 1/2
∫(x+ 1)? ≥0
No matter x is any real number, there is always 2x? +4x+3>0
②3x? -5x- 1>2x? -4x 7
3x? -2x? -5x+4x- 1+7>0
x? -x+6>0
x? -x>-6
(x- 1/2)? >-23/4
∫(x- 1/2)? ≥0
Whether x is any real number, there is always 3x? -5x- 1>2x? -4x 7
( 16) (6,4)
Three. Knowledge development
1-4 CCDA
6 or 12 6 1: 1
(8)①PA = 1/6 PB = 2/6 = 1/3 PC = 2/6 = 1/3 PD = 1/6
(2) It's unfair, because the probability of a chess piece moving to each point is different.
If you want to win as much as possible, you should choose point B or point C.
③PA=8/36=2/9
(9)① If the diagonals of a quadrilateral are perpendicular to each other, then the area of this quadrilateral is equal to half of the diagonal product.