It cost Naomi $7.70 to send 154 text messages. How many text messages did she send
1 answer:
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Let be the amount of the 30% alloy and
the amount of the 60% alloy the metalworker will use. However much is used, the final alloy will have a mass of
kilograms. For each kg of the 30% alloy used, 0.3 kg is copper; similary, each kg of the 60% alloy contributes 0.6 kg, so that
Now,
Answer:
x = 1, -5.56
Step-by-step explanation:
x^2 = -7x - 8
shift -7x and -8 to the other side . Remember when u shift minus changes into plus.
x^2 + 7x + 8 = 0
using quadratic equation formula
in quadratic equation one value comes positive and other comes in negative
a = 1 , b = 7 and c = 8
taking positive sign
x = (-b + ) /2*a
x = (-7 + ) /2*1
x = (-7 + ) /2
x = (-7 + )/ 2
x = -7 + 9 / 2
x = 2/2
x = 1
taking negative sign
(-b - ) /2*a
x = (-7 - ) /2*1
x = (-7 - ) /2
x = -7 - / 2
x = -7 - 4.12 / 2
x = -11.12/2
x = -5.56
therefore x = 1 , - 5.56