Question

find the value of k' if (3,7), (10, 21)
(K+ 7, ²) are to collinear.​

Answer 1

Step-by-step explanation:

We know that points (3,7) , (10,21) & (k+7 , 2) are

collinear.

So , | 3 7 1 |

| 10 21 1 | = 0

| k+7 2 1 |

=> 3(21-2) - 7(10-k-7) + 1(20-21k-147) = 0

=> 3(19) - 7(3-k) + (-21k - 127) = 0

=> 57 - 21 + 7k - 21k - 127 = 0

=> 36 - 14k - 127 = 0

-14k = 127-36 = 91

k = -91/14 = -13/2

Answer 2

Answer:

The point are co-linear so,

ar = x¹( y²-y³)+x²(y³-y¹)+x³(y¹-y²)

0 = 3(21-2)+10(2-7)+(k+7)(7-21)

0 = 3*19 + 10(-5) + (-14)(k+7)

0 = 57 - 50 - 14k - 98

0 = 7-98-14k

14k = -91

k = -13/2 = 6.5