(x + a) (x + b) = x² + (a + b) x + ab
75 * 77=
=(70+5)(70+7)
=70²+(5+7)*70+5*7
=4900+12*70+35
=4900+840+35
=5775
Answer:
r = - 
Step-by-step explanation:
The n th term of a GP is
= a₁ 
where a₁ is the first term and r the common ratio
Here a₁ = 18 and a₆ = -
, then
18
= -
( divide both sides by 18 )
= -
( take the fifth root of both sides )
r =
= - 
3.) 2 × 0.5 = 1
4.) -2 × -0.5 = 1