Here are the solutions to the sequences:
Question 1: Write the next three numbers in each of the following sequences. Say whether each sequence is a constant difference or constant ratio sequence or neither.
a) 3, 6, 9, 12, 15, ...
Step 1: Find the difference between consecutive terms.
$6-3=3$
$9-6=3$
$12-9=3$
$15-12=3$
The difference is constant (3). This is a constant difference sequence.
Step 2: Add the constant difference to find the next three terms.
$15+3=18$
$18+3=21$
$21+3=24$
The next three numbers are 18, 21, 24.
The sequence is a constant difference sequence.
$$\boxed{\text{18, 21, 24; Constant difference}}$$
b) 2, 4, 8, 16, ...
Step 1: Find the ratio between consecutive terms.
$\frac{4}{2}=2$
$\frac{8}{4}=2$
$\frac{16}{8}=2$
The ratio is constant (2). This is a constant ratio sequence.
Step 2: Multiply by the constant ratio to find the next three terms.
$16 \times 2=32$
$32 \times 2=64$
$64 \times 2=128$
The next three numbers are 32, 64, 128.
The sequence is a constant ratio sequence.
$$\boxed{\text{32, 64, 128; Constant ratio}}$$
c) 7, 11, 15, 19, 23, ...
Step 1: Find the difference between consecutive terms.
$11-7=4$
$15-11=4$
$19-15=4$
$23-19=4$
The difference is constant (4). This is a constant difference sequence.
Step 2: Add the constant difference to find the next three terms.
$23+4=27$
$27+4=31$
$31+4=35$
The next three numbers are 27, 31, 35.
The sequence is a constant difference sequence.
$$\boxed{\text{27, 31, 35; Constant difference}}$$
d) 1, 4, 9, 16, ...
Step 1: Check for constant difference.
$4-1=3$
$9-4=5$
$16-9=7$
The differences are not constant.
Step 2: Check for constant ratio.
$\frac{4}{1}=4$
$\frac{9}{4}=2.25$
The ratios are not constant.
Step 3: Observe the pattern. The terms are squares of consecutive integers: $1^2, 2^2, 3^2, 4^2$.
Step 4: Find the next three terms.
$5^2=25$
$6^2=36$
$7^2=49$
The next three numbers are 25, 36, 49.
The sequence is neither a constant difference nor a constant ratio sequence.
$$\boxed{\text{25, 36, 49; Neither}}$$
Question 2: Describe the pattern in each of the following sequences. State whether it is a constant difference or constant ratio sequence or neither. Then fill in the missing numbers.
a) 18, 36, 54, 72, [ ], [ ], [ ]
Step 1: Find the difference between consecutive terms.
$36-18=18$
$54-36=18$
$72-54=18$
The difference is constant (18). This is a constant difference sequence.
Step 2: Add the constant difference to find the missing terms.
$72+18=90$
$90+18=108$
$108+18=126$
The pattern is adding 18 to the previous term. The sequence is a constant difference sequence. The missing numbers are 90, 108, 126.
$$\boxed{\text{Constant difference; 90, 108, 126}}$$
b) 3, 9, 27, [ ], [ ], [ ]
Step 1: Find the ratio between consecutive terms.
$\frac{9}{3}=3$
$\frac{27}{9}=3$
The ratio is constant (3). This is a constant ratio sequence.
Step 2: Multiply by the constant ratio to find the missing terms.
$27 \times 3=81$
$81 \times 3=243$
$243 \times 3=729$
The pattern is multiplying the previous term by 3. The sequence is a constant ratio sequence. The missing numbers are 81, 243, 729.
$$\boxed{\text{Constant ratio; 81, 243, 729}}$$
*c) 1.25, 2.5, 3.75, 5.0, [ ], [ ], [