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In what ratio does the line of the equation 4x + 5y = 21 divide the line segment joining the points (-2, 3) and (4, 5) ?​

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Answer: 1.465 : 1

Explanation:

Slope of the line segment:

m = (5 - 3)/(4 - (-2)) = 2/6 = 1/3

The equation of the line which the line segment lies on is found by:

(y - 3)/(x - (-2)) = 1/3

(y - 3)/(x + 2) = 1/3

(y - 3)/(x + 2) * (x + 2) = 1/3 * (x + 2)

y - 3 = (x + 2)/3 = 1/3 x + 2/3

y = 1/3 x + 11/3

The equation of the line given:

4x + 5y = 21

5y = -4x + 21

y = -4/5 * x + 21/5

Set them equal to each other and solve for x to find their intersection:

1/3 x + 11/3 = -4/5 * x + 21/5

15(1/3 x + 11/3) = 15(-4/5 * x + 21/5)

5 x + 55 = -12 x + 63

17x = 8

x = 8/17

y = 1/3 (8/17) + 11/3 = 8/51 + 181/51 = 189/51

Point (8/17, 189/51)

Distance from right end of segment to intersection:

s = SQRT((4 - 8/17)^2 + (5 - 189/51)^2) = SQRT((60/17)^2 + (66/51)^2) = 3.759

length of segment = SQRT((5–3)^2 + (4 - (-2))^2) = SQRT(4 + 36) = SQRT(40) = 6.324

Distance from the left end to interseciton:

6.324 - 3.759 = 2.555

Ratio of right end to left end:

3.759/2.565 = 1.465

User Mike Adamenko
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