Answer:
a) x = 12 y = 9
b) x = -2 y = -4
c) x = 6 y = -2
Step-by-step explanation:
a)
Equation 1: 6x - 7y = 9
Equation 2: 3x + 2y = 54
Multiply Equation 2 by 2:
⇒ 6x + 4y = 108
Subtract equations:
6x + 4y = 108
<u>- 6x - 7y = 9 </u>
11y = 99
Divide both sides by 11:
⇒ y = 9
Substitute found value of y into Equation 1 and solve for x:
⇒ 6x - 7(9) = 9
⇒ 6x - 63 = 9
⇒ 6x = 72
⇒ x = 12
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b)
Equation 1: 4x - 5y = 12
Equation 2: 2x - 3y = 8
Multiply Equation 2 by 2:
⇒ 4x - 6y = 16
Subtract equations:
4x - 6y = 16
<u>- 4x - 5y = 12 </u>
-y = 4
Divide both sides by -1:
⇒ y = -4
Substitute found value of y into Equation 1 and solve for x:
⇒ 4x - 5(-4) = 12
⇒ 4x + 20 = 12
⇒ 4x = -8
⇒ x = -2
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c)
Equation 1: 4x - 2y = 28
Equation 2: 3x + 3y = 12
Multiply Equation 1 by 3:
⇒ 12x - 6y = 84
Multiply Equation 2 by 4:
⇒ 12x + 12y = 48
Subtract equations:
12x - 6y = 84
<u>- 12x + 12y = 48 </u>
-18y = 36
Divide both sides by -18:
⇒ y = -2
Substitute found value of y into Equation 1 and solve for x:
⇒ 4x - 2(-2) = 28
⇒ 4x + 4 = 28
⇒ 4x = 24
⇒ x = 6
Answer:
85.55
Step-by-step explanation:
i dont know if im right but
1) i took 12 × $6.79 for the total cost ehich totalled out to 81.48
2) i used calcutator.net and put in the sales tax 5% ($4.07)
3) it gave me $85.55 after adding the tax
I think that it is about 20 out of 100.
Answer:
see explanation
Step-by-step explanation:
given 
To rationalise multiply the numerator/denominator by the conjugate of the denominator
the conjugate of 3 + 7i is 3 - 7i, hence
distribute the numerator/denominator
= 
[ note that i² = - 1 ]
= 
= 
= 
+ 
i
= 
+ 
i ← in standard form
