Answer:
36x² - 9y²
Step-by-step explanation:
We see that the given expression (6x + 3y)(6x - 3y) looks just like the expression (a + b)(a - b). When multiplied out, this is a difference of squares identity that I highly recommend you memorise:
(a + b)(a - b) = a² - b²
Here, a = 6x and b = 3y, so plug these in:
(6x + 3y)(6x - 3y) = (6x)² - (3y)² = 36x² - 9y²
It's one of the ways to count it:
3/4 (n + 3) = 9
3/4n + 3/4 * 3 = 9
3/4n + 9/4 = 9
3/4n + 2 1/4 = 9 / - 2 1/4 (both sides)
3/4n = 6 3/4 / : 3/4 (both sides)
n = 9
If a, b, c is an arithmetic sequence then a + c = 2b
a = 1/10; b = 3/20, c = 5/30
a + c = 1/10 + 5/30 = 3/30 + 5/30 = (3+5)/30 = 8/30
2b = 2 · 3/20 = 3/10 = 9/30
8/30 ≠ 9/30
If a, b, c is a geometric sequence then ac = b²
ac = 1/10 · 5/30 = 1/2 · 1/30 = 1/60
b² = (3/20)² = 9/400
1/60 ≠ 9/400
<span>Answer: Neither.</span>
3 3/5 or can be said as three and three fifths
