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The number of boys in ninth grade is 12 less than twice the number of girls There are 51 students in ninth grade How many are girls?
Let's lay out the known information in equations, where B is the number of boys and G is the number of girls. Then we express the number B in terms of G, which is twice as much less 12, or (2G-12) B + G = 51 , and B = 2G - 12 Now, replace the B in the first equation with its value from the second equation (2G - 12) + G = 51 Remove the brackets 2G - 12 + G = 51 Add 12 to both sides 2G + G = 51 + 12 3G = 63 Divide both sides by 3 G = 21 Now, to check if we're right, Replace G in the first equation B + 21 = 51 B = 30 If that's right then 30 = 2(21) - 12 30 = 42 - 12 And it is, so we know that there are 21 girls and 30 boys in ninth grade.
What is thember missing number one-fourth 8?
One fourth of 8 is 2.
What is the slope of the line that passes through the points (-12 -17) and (21 5)?
Points: (-12, -17) and (21, 5) Slope: 2/3
Solve by completing the square of by quadratic equation -84x2 8x-12?
hmm... i don' think you have the completed the question. This one is pretty hard! Solving quadratics can be difficult and ompleting the square is one method for solving a quadratic equation.Is the equation -84x2-8x-12=0 or -84x2+8x - 12 = 0 or -84x2 = 8x - 12?If it is the first one:Factor out the 4:-4 (21x2 + 2x + 3) = 021x2 + 2x + 3 = 0 (divide by 21 each term to both sides)x2 + (2/21)x + 3/21 = 0 (subtract 3/21 to both sides)x2 + (2/21)x = -3/21 (add (1/2 of 2/21)2 or (1/21)2 to both sides)x2 + (2/21)x + (1/21)2 = -3/21 + 1/212(x + 1/21)2 = -63/212 + 1/212(x + 1/21)2 = -62/212 (square root to both sides)x + 1/21 = ± √-62/212x + 1/21 = ± (i/21)√62 (subtract 1/21 to both sides)x = -1/21 ± (i/21)√62x = -1/21 (1 - i√62) orx = -1/21 (1+ i√62)If it is the third one:-84x2 = 8x - 12 (divide by -84 to both sides)x2 = -(2/21)x + 3/21 (add (2/21)x to both sides)x2 + (2/21)x = 3/21 (add (1/2 of 2/21)2 or (1/21)2 to both sides)x2 + (2/21)x + (1/21)2 = 3/21 + 1/212(x + 1/21)2 = 63/212 + 1/212(x + 1/21)2 = 64/212 (square root to both sides)x + 1/21 = ± √64/212x + 1/21 = ± 8/21 (subtract 1/21 to both sides)x = -1/21 ± 8/21x = -1/21 + 8/21 = 7/21 = 1/3 orx = -1/21 - 8/21 = -9/21 = -3/7
What is the square root of 84 simplify?
It is: 2 times the square root of 21 and it's an irrational number
