Answer:
A) [First try is correct for all U1 to U4]
Step-by-step explanation:
1. Trying each option
(let x = 1,2,3,4) since it goes from U1 to U4 (Geometric sequence)
A.) 10(-4/5)^x
10(-4/5)^1 = -8
10(-4/5)^2 = 6.4
10(-4/5)^3 = -5.12
10(-4/5)^4 = 4.096
The number is 6.25.
We will set up an equation for this. Let x be the unknown number. Subtracting 1.05 from it gives us
(x-1.05)
Multiplying the difference by 0.8 would give us
0.8(x-1.05)
Adding 2.84 to the product would give us
0.8(x-1.05)+2.84
Dividing the sum by 0.01 would give us
[0.8(x-1.05)+2.84]/0.01 = 700
We will start working backward, cancelling the division by 0.01 first by multiplying:
([0.8(x-1.05)+2.84]/0.01)*0.01 = 700*0.01
0.8(x-1.05)+2.84 =7
Subtract 2.84 from both sides:
0.8(x-1.05)+2.84-2.84 = 7-2.84
0.8(x-1.05) = 4.16
Use the distributive property on the left side:
0.8*x - 0.8*1.05 = 4.16
0.8x - 0.84 = 4.16
Add 0.84 to both sides:
0.8x - 0.84+0.84 = 4.16+0.84
0.8x = 5
Divide both sides by 0.8:
0.8x/0.8 = 5/0.8
x = 6.25
Some equivalent fractions are 2/6 , 3/9 , 4/12<span />
Answer:
AD = 85
Step-by-step explanation:
AD = AB + BC + CD ( substitute values , noting AB = CD = 20 ) , then
AD = 20 + 45 + 20 = 85
