Okay so the value of X is 9x^2/7
a.
b.
The metal obey this law for values of strain until 0.05, where we have a linear relationship (each increase of 0.01 in the strain causes an increase of 100 in the stress). After this point, we don't have a linear relationship anymore.
c. Since an increase of 0.01 in the strain causes an increase of 100 in the stress, the slope is:

Now, calculating the coefficient b (y-intercept), we have:

So the equation is:

d.
The maximum value of stress is 560, and occurs at strain = 0.07.
Answer: Therefore it must be the first one, 40
Step-by-step explanation: Vertical angles are always congruent, which means that they are equal. x = 40