Mrs Bopha, used phone that had 7 numbers. Som didn't clear her phone number.Som remember 4 numbers in the first that had 9 ,8 , 7 and 7 Som didn't clear serial number 5 about 1 or 2.For serial number 6 didn't remember. But Som remember that serial number7 equal 5 minus serial number 6.How many time that Som  should be chose right phone 's number to Mrs Bopha?

integrate ∫dx/√((x^2+1)(ln(x^2+√(x^2+1)))

Solve the equation : 58.54*x^2+19620*x^(1.85)-11485.54=0

Find the function satisfying the following conditions:

f(-6)=2400,f(-4)=432,f(-3)=120,f(-2...

Let function so that