Question

Help!! Definate Medal!!!
Which lines are perpendicular to 5x + 4y = 8?

Choose all answers that are correct.

4y=-5x+4
4y= 5x + 12
5y = 4x + 15
5y = –4x – 15
My answer is 4y=-5x+4.. what do you think

Answer 1

5x + 4y = 8
4y = -5x + 8
y = -5/4x + 2

a perpendicular line will have a negative reciprocal slope....that means just flip the slope and change the sign. The slope in the original equation is -5/4...but a perpendicular line will have a slope of 4/5....see how I flipped the slope and changed the sign. So any equation with a slope of 4/5 will be perpendicular.

5y = 4x + 15 -- divide by 5
y = 4/5x + 3.....the slope is 4/5....that is the negative reciprocal slope of -5/4...so this is your perpendicular line.

Answer 2

Thanks sooo much