Please help, I would appreciate it

-5x + 8y = -21

3x - 4y = 15

8y = 5x - 21

y = 5/8x - 21/8

3x - 4y = 15

-4y = -3x + 15

y = 3/4x - 15/4

5/8x - 21/8 = 3/4x - 15/4

-1/8x = -9/8x

x = 9

3x - 4y = 15

3(9) - 4y = 15

27 - 4y = 15

-4y = -12

y = 3

(9, 3)

  (9, 3)

Step-by-step explanation:

My favorite way to solve equations like this is using a graphing calculator. For Desmos, one only needs to type the equations into the input column, click on one of them, and highlight the point of intersection to see the coordinates there.

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The usual ways to solve these are by substitution or elimination. Another way they can be solved is using Cramer's rule, which provides a formula for the solution based on the coefficients.

  ax +by = c

  dx +ey = g

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  x = (bg -ec)/(bd -ea) . . . . . . note the crossing pattern of the values in the products

  y = (cd -ga)/(bd -ea) . . . . . . the denominator is the same as above

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Using these formulas, we get ...

  x = (8(15) -(-4)(-21))/(8(3) -(-4)(-5)) = (120 -84)/(24 -20) = 36/4 = 9

  y = (-21(3) -15(-5))/4 = (-63 +75)/4 = 12/4 = 3

The solution is (x, y) = (9, 3).

Doing the same by elimination involves the same amount of math and a lot more writing.

location: point 0

step-by-step explanation:

well, -8 to 10 on a number line is 18 spaces.

1/9 of 18 is 2.

so, 4/9 of 18 must be 8.

8 spaces from -8 (a) is 0.

so, 4/9 of the way from -8 to 10 is 0!

hello,

b) 62.47% of the students are between 14 and 18 years old.

step-by-step explanation:

mean = 15 and standard deviation = 2

student between 14 to 18

formula used z-score

for age 14 , z score

using z-table , p(z> -0.5)=0.3085

for age 18 , z score

using z-table , p(z< 1.5)=0.9332

p(-0.5< z< 1.5)=0.9332-0.3085 = 0.6247

thus, 62.47% of the students are between 14 and 18 years old.

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