Alan

Any multiple of the x^4 term will result in a power of x greater than x^3, so you can reduce this to (-3x + 2)^3

The only term that will produce an x^3 is the (-3x) term, so the coefficient of the x^3 term is just (-3)^3 or -27.

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Total marks of boys = 35*50 → 1750

Total marks of girls = 46*g_ave

Total marks of class = (35 + 46)*40 → 81*40 → 3240

So we must have:  1750 + 46*g_ave = 3240

 46*g_ave = 3240 - 1750 

g_ave = (3240 - 1750)/46 ≈ 32.4

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This might help:

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Because it is n/m that you want to get on its own (ie the larger number divided by the smaller one), so you want to get n on its own first.

Let the numbers be n and m, with n > m

n + m = 5(n - m)

Distribute the 5 on the right

n + m = 5n - 5m

Add 5m to both sides

n + 6m = 5n

Subtract n from both sides

6m = 4n

Divide both sides by 4

1.5m = n

Divide both sides by m

1.5 = n/m

or n/m = 1.5.    This is the ratio of the larger number to the smaller.

There is nothing in the original expression to indicate that 5(7-5) has been factored from (35 - 25).  If it had been the correct way to express the result would have been 60/(5(7 - 5))

60/5(7 - 5) has an implied multiplication so should be read as 60/5*(7-5)

To avoid ambiguity either use parentheses or write as \(\frac{60}{5}(7-5)\text{ or}\frac{60}{5(7-5)}\) as appropriate.

Nor should they have believed you!  See my reply #5.

No Gh0sty!  

Parentheses first:  60/5*2

Divide and Multiply have the same precedence so you work from left to right:

60/5*2 → 12*2 → 24

The domain refers to all allowable values of x.  Here that is from -infinity to + infinity (R)

The range refers to the resulting values of y (or fog(x)).  Since (x^2 -1)/(x^2 + 1) can range from -1 (when x is 0) to +1 (when the absolute value of x is very large) then the angle whose cosine is (x^2 -1)/(x^2 + 1) can be any positive or negative value. So the range is -infinity to +infinity as well (R).

"if f(x)=cos^-1(2x-1) and g(x)=x^2/1+x^2 find domain of fog(x)??"

The following should help:

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