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The Answer is <u><em>7.88</em></u>
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<span>x² +y² -4x -6y +8=0
(x² -4x) +(y² -6y) = -8
We are going to complete square for x and y,
it should look like a²+2ab+b² = (a +b)², or </span>a²-2ab+b² = (a -b)²,
<span>
(x²-2*2x+2²) -2² + (y²-2*3y +3²)-3²=- 8
(x-2)²+(y-3)²-4-9=-8
</span>(x-2)²+(y-3)²=-8+13
(x-2)²+(y-3)²=5
<span>
Formula a circle (x-h)²+(y-k)²=R², where vertex has coordinates (h, k)
So , for our circle vertex (2,3) and radius = </span>√5<span>
</span>
3x + 5y = 10 Subtract 3x from both sides.
5y = -3x + 10 Divide both sides by 5.
y = -3/5x + 2
Let the original cost of laptop=x
Savings=20% = 20/100
Saved amount = $140
Original cost = saved amount * 1/savings
x = 140* 100/20
x = $7000
Your mistake was in this part 9 x 1/100 . After the decimal point the place value starts with tenths so you should write 9 x 1/10 .
Place values
Before the decimal
point
3 ones = 3 x 1
0 tens = 0 x 10
1 hundreds = 1 x 100
After the decimal
point
9 tenths = 9 x 1/10
0 hundredths = 0 x 1/100
3 thousandths= 3 x 1/1000
1 x 100 + 0 x 10 + 3 x 1 + 9 x 1/10 + 0 x 1/100 + 3 x 1/1000
100 + 0 + 3 + 0.9 + 0 + 0.003
100 + 3 +
0.9 + 0.003 = 103.903
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