In Which of the following case , A Straight line slope will be upward given linear equation is Y = a+bX.

The slope of a straight line in a linear equation Y = a + bX will be upward when the coefficient b is positive.

Here's the step by step explanation:

1. In the linear equation Y = a + bX, 'b' is the slope of the line.

2. The slope of a line is a measure of how steep the line is.

3. If 'b' is positive, the line will slope upwards as we move from left to right on the graph. This is because for every increase in X, Y increases (since we're adding a positive number to Y).

4. If 'b' is negative, the line will slope downwards as we move from left to right on the graph. This is because for every increase in X, Y decreases (since we're adding a negative number to Y).

5. If 'b' is zero, the line is horizontal. This is because no matter what value X takes, Y always remains the same (since we're adding zero to Y).

So, in the case of the linear equation Y = a + bX, the slope of the line will be upward if 'b' is positive.