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Zorluk: OrtaParallel and Perpendicular Lines

In the standard (x,y)(x, y) coordinate plane, the line L1L_1 is parallel to the line y=3x7y = 3x - 7. The line L2L_2 is perpendicular to L1L_1 and passes through the point (6,5)(6, 5). If the yy-intercept of L2L_2 is (0,c)(0, c), what is the value of cc?

Cevap: 7

Cevap

The value of cc is 77.
Since the line L1L_1 is parallel to y=3x7y = 3x - 7, its slope is 33. The line L2L_2 is perpendicular to L1L_1, so its slope is the negative reciprocal of 33, which is 13-\frac{1}{3}. Using the point-slope formula with the point (6,5)(6, 5) yields the equation of L2L_2: y5=13(x6)y - 5 = -\frac{1}{3}(x - 6), which simplifies to y=13x+7y = -\frac{1}{3}x + 7. The yy-intercept of this line is (0,7)(0, 7), which gives c=7c = 7.

Adım Adım Çözüm

1
Determine the slope of line L1L_1.
Slope of L1L_1 is 33.
Parallel lines have equal slopes, and the given reference line y=3x7y = 3x - 7 has a slope of 33.
2
Determine the slope of line L2L_2.
Slope of L2L_2 is 13-\frac{1}{3}.
Perpendicular lines have slopes that are negative reciprocals of each other.
3
Find the equation of line L2L_2.
The equation is y=13x+7y = -\frac{1}{3}x + 7.
Use the point-slope form yy1=m(xx1)y - y_1 = m(x - x_1) with point (6,5)(6, 5) and slope 13-\frac{1}{3}.
4
Identify the yy-intercept constant cc.
c=7c = 7.
The equation of L2L_2 is in slope-intercept form y=mx+by = mx + b, meaning the yy-intercept is (0,7)(0, 7).

Anahtar Kavram

The relationship between the slopes of parallel lines (which are equal) and perpendicular lines (which are negative reciprocals).
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