Tham khảo tài liệu 'education english 2', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | ESSENTIAL PRACTICE WITH MATH x1. To divide x4 by x1 you just subtract 4 1 to get x3. The equation is now y- - r- . We divide y3 by y to get y2 in the numerator. x3 f- 2. 6. a. First subtract 4 from both sides of the equation 2x 4 12 to yield 2x 16. Next divide everything by 2 to get x 8. 7. c. Substitute 5 in for b in the given equation. Thus b2 b -52 5 25 - 5 ị 20 4g. 6 20 6 3 . 8. d. Put 2 in for x in the equation 3x2 2x 5. Thus the equation becomes 3 2 2 2 2 5 3 4 - -4 5 12 4 5 21. 9. is greater than 5 then you can write b 5. In order to compare this to b 3 just add 3 to both sides of the inequality b 3 5 3 or b 3 8. Thus b 3 must be greater than 8. 10. a. x 2 2 4x can be rewritten as x 2 x 2 0. So you know that x 2 0 or x 2. 11. b. 5x 6 3x 16 can be simplified by first subtracting 3x from both sides to yield 2x 6 16. Now you add both 6 to both sides to get 2x 22. Dividing both sides by 2 you get x 11. 12. d. Replace every q with a 6 in the equation 5q q2 to yield 5 6 - 6 2 30 - 36 -6. 13. d. x2 2x 15 0 can be factored into two sets of parentheses x x . Because the coefficient on the x2 is 1 we know the missing numbers add to 2 because the coefficient of x is 2 and multiply to 15 the lone number is 15 . Thus the numbers are 3 and 5. The equation is equivalent to x 3 x 5 0. This means x 3 0 and x 5 0 or x 3 and x 5 respectively. 14. c. 5x 5 30 can be simplified by first adding 5 to both sides 5x 35. Next divide by 5 to yield x 7. 15. a. Divide both sides of 3x 9 by 3 but be sure to flip the sign Thus you get x 3. 16. a. 8x3y 2x5y9 can first be reduced to 16x3yx5y9. If you have the same base when multiplying exponents remember to just add the powers. For the x terms you add 3 5 to get x8. Since y is the same as y1 when you add the powers of the y terms you get 1 9 or y10. Thus the final answer is 16x8y10. 17. c. The given equation is 9 P 1 2 P . First we distribute the 9 to get 9P 9 2 P . Next we distribute the 2 and the inequality becomes 9 P 9 2 P
