You should know that:
(a+b)(a+b)(a+b)
=a(a+b)(a+b)+b(a+b)(a+b)
=a(a²+2ab+b²)+b(a²+2ab+b²)
=a³+2a²b+ab²+a²b+2ab²+b³
=a³+3a²b+3ab²+b³
-----------------
If a=5x and b=-4y
(5x+(-4y))³
=(5x-4y)³
=(5x)³+3(5x)²(-4y)+3(5x)(-4y)²+(-4y)³
=125x³+3(25x²)(-4y)+15x(16y²)-64y³
=125x³+75x²(-4y)+240xy²-64y³
=125x³-300x²y+240xy²-64y³
Answer:
Using ∣x∣>a⇒x<−a or x>a, we get
∣3x−7∣>4⇒3x−7<−4 or 3x−7>4
⇒3x<3 or 3x>11⇒x<1 or x>
3
11
⇒x∈(−∞,1)∪(
3
11
,∞).
Answer:
B
Step-by-step explanation:
using the tangent ratio on the triangle on the right and the exact value
tan60° = 
, then letting the altitude be h
tan60° = 
= 
= ( multiply both sides by h )
11
= h × ( divide both sides by )
11
= h
using the sine ratio in the triangle on the left and the exact value
sin45° = 
, then
sin45° = 
= 
= 
= ( cross- multiply )
× x = 22 ( divide both sides by )
x = 22
