Answer:
5 (5x1) , -10 -(5x2), 20(10x2), -40 -(20x2), 80(40x2)
so the next number should be previous number in the sequence multiplied by 2 and a negative sign.
-`(80x2) = -160
Answer:

________

Step-by-step explanation:
Given

Line up the numbers

Multiply the top number by the bottom number one digit at a time starting with the ones digit left(from right to left right)
Multiply the top number by the bolded digit of the bottom number

Multiply the bold numbers: 1×4=4

Multiply the bold numbers: 2×4=8

Multiply the top number by the bolded digit of the bottom number

Multiply the bold numbers: 1×1=1

Multiply the bold numbers: 2×1=2

Add the rows to get the answer. For simplicity, fill in trailing zeros.

adding portion

Add the digits of the right-most column: 4+0=4

Add the digits of the right-most column: 8+1=9

Add the digits of the right-most column: 0+2=2

Therefore,

________

Answer:
7/8
Step-by-step explanation:
When 16 students are playing kickball, there are 16/16 students on the field. After 2 leave, this becomes 16-2/16, therefore 14/16 which is divisible by 2. and therefore 7/8, which the numerator and denominator have no common divisors.
The average cost in 1990 is <span>$12,841.</span>
When a quadratic equation ax^2+bx+c has a double root, the discriminant,
D=b^2-4ac=0
Here
a=2,
b=b,
c=18
and
D=b^2-4ac=b^2-4*2*18=0
solve for b
b^2-144=0
=> b= ± sqrt(144)= ± 12
So in order that the given equation has double roots, the possible values of b are ± 12.