Will85237

I think what you're trying to say is this:

-1 < x/2 < 1

This is a range for the possible values of x, but they mean nothing without an equation. How

However, it can be simplified by multiplying by 2.

-2 < x < 2

Yes, 4*3x = 12x.

Moles of HCl produced is:

mass/atomic mass

=64.15/(35.5+1)

=1.76mol

Moles of H2 used is:

mass/atomic mass

=2.07/1

=2.07mol

By dividing the the moles of H2 used by the moles of HCl created, we get the percentage yield of the reaction:

1.76/2.07

=0.85

=85%

Note that I may have rounded too much, you might need to use more accurate values for the atomic masses.

DISCLAIMER: I have never calculated percentage yield in chemistry so I might be wrong.

40% of 32.55 can be calculated as:

0.40*32.55

=13.92

Hooke's Law:

F=kx

F is the force on the spring. Force is the product of mass and acceleration, so it can written as follows.

ma=kx

k is the spring constant, which is given. x is displacement, which is what we're trying to find.

x=ma/k

By subsituting the variables in (9.81 = acceleration due to gravity):

x=10*9.81/70

x=1.40

The spring will stretch 1.4 metres.

Because of the sides given for the angle, we need sin().

sinx = Opp/Hyp

sin35 = 7/10

0.574 != 0.7

Because the sin() of the given angle is not equal to the opposite side length divided by the hypotenuse side length, we know the triangle is impossible.

The tallest student is 1.52m tall. It's given in the question...

I think you might hav made a typo.

Well, 40% of 50 can be written as:

$${\mathtt{0.4}}{\mathtt{\,\times\,}}{\mathtt{50}} = {\mathtt{20}}$$

And 50% of forty can be written as:

$${\mathtt{0.5}}{\mathtt{\,\times\,}}{\mathtt{40}} = {\mathtt{20}}$$

So yes, they are the same.

cos = sqrt(1-sin^2)

cos = sqrt(1-(-3/5)^2)

cos = sqrt(1-9/25)

cos = sqrt(16/25)

cos = 4/5

acos only works for numbers between -1 and 1 because of the unit circle has a radius of 1.