Rachel's cell phone company charges $0.10 per minute. She used 350 minutes last month and paid $84. writ and solve a linear equa
1 answer:
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Answer:
Option b is correct (8,13).
Step-by-step explanation:
7x - 4y = 4
10x - 6y =2
it can be represented in matrix form as
A=
X=
B=
i.e, AX=B
or X= A⁻¹ B
A⁻¹ = 1/|A| * Adj A
determinant of A = |A|= (7*-6) - (-4*10)
= (-42)-(-40)
= (-42) + 40 = -2
so, |A| = -2
Adj A=
A⁻¹ = / -2
A⁻¹ =
X= A⁻¹ B
X=
X=
X=
X=
x= 8, y= 13
solution set= (8,13).
Option b is correct.