jika titik-titik (2,7),(6,-1), dan (9,m) terletak dalam satu garis lurus, maka nilai m adalah... a.3 b.2 c.-1 d.-7
Matematika
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Pertanyaan
jika titik-titik (2,7),(6,-1), dan (9,m) terletak dalam satu garis lurus, maka nilai m adalah...
a.3
b.2
c.-1
d.-7
a.3
b.2
c.-1
d.-7
1 Jawaban
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1. Jawaban johannahelina
A = (2,7)
B = (6,-1)
C = (9,m)
AB = (6,-1) - (2,7) = (4,-8)
BC = (9,m) - (6,-1) = (3,m + 1)
AB = k × BC
(4,-8) = k × (3,m + 1)
(4,-8) = (3k, k(m + 1))
4 = 3k
4/3 = k
k(m + 1) = -8
4/3(m + 1) = -8
4/3m + 4/3 = -8
4/3m = -28/3
m = -28/3 × 3/4
m = -7 (D)