Answer:
<u>The sum of their ages now is 13</u>
Step-by-step explanation:
Dally's age = x
Dilly's age = x - 7
In 4 years time Dilly will be half Dally’s age, therefore:
Dilly's age plus four equals to half of Dally’s age plus four,
replacing with the values and variables we know:
x - 7 + 4 = (x + 4) /2
x - 3 = (x + 4) /2
2x - 6 = x + 4 (Multiplying by 2 at both sides)
2x - x = 4 + 6 (Like terms)
x = 10 ⇒ x - 7 = 3
<u>The sum of their ages now is 13 (10 + 3)</u>
Solve the following system:
{6 t - 5 s = -4 | (equation 1)
{-r - 4 s + 3 t = -4 | (equation 2)
{-2 r - 4 s - 4 t = -9 | (equation 3)
Swap equation 1 with equation 3:
{-(2 r) - 4 s - 4 t = -9 | (equation 1)
{-r - 4 s + 3 t = -4 | (equation 2)
{0 r - 5 s + 6 t = -4 | (equation 3)
Subtract 1/2 × (equation 1) from equation 2:
{-(2 r) - 4 s - 4 t = -9 | (equation 1)
{0 r - 2 s + 5 t = 1/2 | (equation 2)
{0 r - 5 s + 6 t = -4 | (equation 3)
Multiply equation 1 by -1:
{2 r + 4 s + 4 t = 9 | (equation 1)
{0 r - 2 s + 5 t = 1/2 | (equation 2)
{0 r - 5 s + 6 t = -4 | (equation 3)
Multiply equation 2 by 2:
{2 r + 4 s + 4 t = 9 | (equation 1)
{0 r - 4 s + 10 t = 1 | (equation 2)
{0 r - 5 s + 6 t = -4 | (equation 3)
Swap equation 2 with equation 3:
{2 r + 4 s + 4 t = 9 | (equation 1)
{0 r - 5 s + 6 t = -4 | (equation 2)
{0 r - 4 s + 10 t = 1 | (equation 3)
Subtract 4/5 × (equation 2) from equation 3:
{2 r + 4 s + 4 t = 9 | (equation 1)
{0 r - 5 s + 6 t = -4 | (equation 2)
{0 r+0 s+(26 t)/5 = 21/5 | (equation 3)
Multiply equation 3 by 5:
{2 r + 4 s + 4 t = 9 | (equation 1)
{0 r - 5 s + 6 t = -4 | (equation 2)
{0 r+0 s+26 t = 21 | (equation 3)
Divide equation 3 by 26:
{2 r + 4 s + 4 t = 9 | (equation 1)
{0 r - 5 s + 6 t = -4 | (equation 2)
{0 r+0 s+t = 21/26 | (equation 3)
Subtract 6 × (equation 3) from equation 2:
{2 r + 4 s + 4 t = 9 | (equation 1)
{0 r - 5 s+0 t = (-115)/13 | (equation 2)
{0 r+0 s+t = 21/26 | (equation 3)
Divide equation 2 by -5:
{2 r + 4 s + 4 t = 9 | (equation 1)
{0 r+s+0 t = 23/13 | (equation 2)
{0 r+0 s+t = 21/26 | (equation 3)
Subtract 4 × (equation 2) from equation 1:
{2 r + 0 s+4 t = 25/13 | (equation 1)
{0 r+s+0 t = 23/13 | (equation 2)
{0 r+0 s+t = 21/26 | (equation 3)
Subtract 4 × (equation 3) from equation 1:
{2 r+0 s+0 t = (-17)/13 | (equation 1)
{0 r+s+0 t = 23/13 | (equation 2)
{0 r+0 s+t = 21/26 | (equation 3)
Divide equation 1 by 2:
{r+0 s+0 t = (-17)/26 | (equation 1)
{0 r+s+0 t = 23/13 | (equation 2)
v0 r+0 s+t = 21/26 | (equation 3)
Collect results:Answer: {r = -17/26
{s = 23/13 {t = 21/26
6. Answer: B
Length of 1 side is 6
Perimeter is 6×6 = 36
5 times larger
Length of one side 6×5 = 30
Perimeter is the 30×6 = 180
180/36 = 5 Perimeter is 5 times greater
7. Answer: H
Find the whole number of squares in the shape given - 22 squares
22 × 10ft = 220 feet
8. Answer: F
((12-3)×3) + (4×3) = (9×3) + 12
= 27 + 12
= 39 ft^2
9. Answer: C
Because the arrow is pointing to the left, the answer to the solution set needs to be less than the the number the dot is on.
A solid dot on a number means that that number is included in the solution set.
In the picture the solid dot is on 4.5, so the solution set needs to be equal to or less than 4.5.
The answer is:
{x | x ≤ 4.5}
18 inch diameter = 9 inch radius
Sphere Volume = <span> 4/3 • <span>π <span>• r³
</span></span></span><span>Sphere Volume = <span> 4/3 * PI * 9^3
</span></span><span>Sphere Volume = <span> 4/3 * PI * 729
</span></span><span><span>Sphere Volume = </span>3,053.628 </span>
