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The Solving for the y-intercept exercise used to appear under the Algebra I Math Mission. This exercise finds the y-intercepts on linear graphs.

## Types of Problems

There are two types of problems in this exercise:

1. Find the y-intercept of the equation: This problem provides a linear equation written in standard form. The student is asked to find the y-intercept of the equation and provide the answer in an ordered pair slot.
2. Find the b in the formula: This problem provides an equation in slope-intercept form (with b unknown) and a point. The student will use the point to find the y-intercept of the line.

## Strategies

Solving linear equations and substituting values for variables are needed to perform this exercise in the standard way. Graphing could be used to avoid these skills.

1. The y-intercept is found by replacing x with zero and solving.
2. Since the Find the y-intercept of the equation problem is practically the same, dividing the isolated number on the right by the coefficient to the y will always provide the single number that needs to be inserted.
3. On the Find the b in the formula problem, If the point is $(x,y)$ and the equation is $y=mx+b$, the answer will be $y-mx$.

## Calculator Programs for TI83/84 series

For the Find the b in the formula problem:

Prompt X,Y,M
Disp Y-MX>Frac

## Real-life applications

1. Problems like this occur on SATs and other standardized tests.
2. Linear models are common in business and the sciences and the y-intercept often provides information about the model such as initial values.