Let x = your number.
x^2 - 21 = 4x. Subtract 4x from both sides.
x^2 - 4x - 21 = 0. Factor.
(x - 7) (x + 3) = 0. Set each term to 0.
x + 3 = 0. Subtract 3 from both sides.
x = -3. This is the negative solution.
Set the other term equal to zero.
x - 7 = 0. Add 7 to each side.
x = 7. This is the positive solution.
Solution of a linear inequality
The solution of a linear inequality is the ordered pair that is a solution to all inequalities in the system and the graph of the linear inequality is the graph of all solutions of the system. Graph one line at the time in the same coordinate plane and shade the half-plane that satisfies the inequality.
The scale is a representation of what the drawing is to real life. The drawing will tend to be represented by a fixed figure such as 1 cm. In this case for every cm of drawing it is a representation of 8 millimetres in real life, therefore the drawing is bigger than the object.
1. 8/9 ÷ 4/9 is done by inverting the divisor (4/9) and then multiplying:
(8/9)(9/4) = 8/4 = 2 (answer)
2. 1/3 ÷ 6 is done similarly: (1/3)(1/6) = 1/18 (answer)
3. 4 ÷ 1/5 = 4 * 5 = 20 (answer)
4. 7 1/2 ÷ 1/4 = (15/2)(4/1) = 30 (answer)
I believe the answer is the second one I am in the same class.
