You are heating liquid in a chemistry lab. Five minutes ago, the temperature of the liquid was -4 degrees Celsius. Since then, it has been going up at a steady rate of 2 degrees per minute.
A.Write an equation that tells you the relationship between temperature and time at any given time. designate the current time as 0.
B. Use your equation to predict the temperature of the liquid 15 minutes from now.
Your daughter shuold know that the equation of a line can be written as y = mx + c where m is the gradient and c is the y-intercept. Your daughter should also know what a y-intercept is. Both these things will be in her class notes or textbook.
In the question you've posted, y is replaced by T and x is replaced by t.
So the equation yuo need will look like T = mt + c.
The T-intercept (think y-intercept), that is, the value of c is given as -4 and the gradient m is given as 2.
You could use Mr. fantastic's method or you can look up somthing called Arithmetic Series.
Where Un = a+(n-1)d
where n is your number of term,
d is the difference between each term, in this case = 2
a is the first value of the term.
Let's say, our term was five since five mins.
We have -4=a+(5-1)*2
Rearrange to find a.
And you have your formula or equation.
Hope this helps.