Find the value of x: log6 (5x + 9)= 4

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{x + y = 9, 1/x + 1/y = 1/2} Find x and y.

leads to

but 
so

this means


which leads to


so that  or 
then we can see:
{ (3,6), (6,3) }

The variables x and y satisfy the equation y=A(b^-x), where A and b are constants. The graph of ln y against x is a straight line passing through the points (0, 1.3) and (1.6, 0.9). Find the values of A and b, correct to 2 decimal places.

so this means

and so

Is this sequence geometric or arithmetic or neither: 3,5,9,15 ?

9-5=4
5-3=2
so it is not arithmetic

15/9=5/3

so it is not geometric either
... so neither

If a person invested a third of her money at 6% and two thirds at 9% and received $450 in interest, find the total money invested.

log7 ( ¼w + 40) = 2; w = _______________

raise 7 to both sides to get:

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A student scored a 78 and 93 on his first two assignments respectively. He wants an average between 88 and 90. Write a compound inequality representing the possible values for a third assignment so his average is between 88 and 90.

88 < (x+78+93)/3 < 90