Simple calculation of 999-98 + 37 + 6

Simple calculation of 999-98 + 37 + 6

999-98+37+6
=999-98+37+(1-2+3+4)
=(999+1)-(98+2)+(37+3)+4
=1000-100+40+4
=900+44
=944

99 + 999 + 9999 + 99999, simple calculation
 

It is known that a = 1 is a root of the equation a cube + a square - A-1 = 0. Please find another root by factorization

A cube + a square - A-1 = 0
(a³＋a²)－(a＋1)=0
a²(a＋1)－(a＋1)=0
(a²－1)(a＋1)=0
(a＋1)(a－1)(a＋1)=0
So a + 1 = 0, a = - 1
Or A-1 = 0, a = 1
The other root of the equation is - 1

The number of boys is 1.2 times that of girls, and there are 80 more boys than girls. How many boys and girls are there in grade six?

The number of female students is x and that of male students is 1.2x
1.2x-x=80
0.2x=80
x=400
Number of male students: 1.2 * 400 = 480

If the root sign 2x is meaningful, then x =...; when x... X + 3 has a square root

(1) If the root sign (2x) is meaningful, then x ≥ 0
(2) When x ≥ - 3, x + 3 has square root

The sum of a, B, C and C is 26. The number of a is 1 times larger than that of B. the sum of two times of a and C is 18 times larger than that of B

Suppose a is a, B is B and C is C. according to the meaning of the question, the following equations are formed
a+b+c=26
a-b=1
2*a+c-b=18
Just solve the equations
a=10 b=9 c=7

Three negative numbers between negative 1 and 0 three negative numbers between negative 1 / 5 and 0 three negative numbers between negative 1 and negative 2 three negative numbers

There are three negative numbers between negative 1 and 0: - 0.9 - 0.8 - 0.7
There are three negative numbers between 1 / 5 and 0: - 1 / 6, - 1 / 7, - 1 / 10
There are three negative numbers between negative 1 and negative 2: - 1.1 - 1.2 - 1.3

A, B and C all have deposits in the bank. B's deposit is 100 yuan less than twice of a's. C's deposit is 300 yuan less than the sum of a and B's. A's deposit is 25 yuan less than C's?

Set a deposit X Yuan & nbsp; & nbsp; & nbsp; & nbsp; X = (x + 2x-100-300) × 25 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = (3x-400) × 25 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 65x-160 & nbsp; X + 160 = 65x-160 + 160x + 160-x = 65x-x & nbsp; 160 △ 15 = 15x △ 15 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 8002 × 800-100 = 1600-100 = 1500 (yuan) 800 △ 25 = 2000 (yuan) a: 800 yuan is deposited by Party A, 1500 yuan by Party B and 2000 yuan by Party C

If the equation (SiNx) ^ 2 - (2 + a) SiNx + 2A = 0 has two real roots on X ∈ [- π / 6,5 π / 6], find the value range of real number a

A:
(sinx)^2-(2+a)sinx+2a=0
(sinx-2)(sinx-a)=0
Because: - 1

1+2+3+4+5+6+7+8+9+.+120+150=?

=（1+150）×150÷2
=151×75
=11325