7th Grade problems

I have a few solved problems for my 7th Grade friends. This will be useful for you to solve the problems at school. Just go through them and understand and try it by using your own examples.

Problem No.1
Find the sum of 2x⁴ – 3x² + 5x + 3 and 4x + 6x³ – 6x² – 1.

(2x⁴ – 3x² + 5x + 3) + (6x³ – 6x² + 4x – 1) = 2x⁴ + 6x³ – 3x² – 6x² + 5x + 4x + 3 – 1

= 2x⁴ + 6x³ – (3+6)x² + (5+4)x + 2

= 2x⁴ + 6x³ – 9x² + 9x + 2

Problem No. 2

A farmer grows 252 kilograms of Mangoes. He sells them to a grocer who divides them into 5 kilogram and 2 kilogram bags. If the grocer uses the same number of 5 kg bags as 2kg bags, then how many bags did he use in all?

Answer:

     Let x = total number of bags

       5(1/2 x) + 2 (1/2 x) = 252

                  2.5x + 1x = 252

                       3.5x = 252

                          x = 72 bags.

Problem No.3

Solve the a − b = 4 and a + b = 5, then find the value of a & b.

Solution:

a − b = 4. (1)

a + b = 5. (2)

(1) + (2) ⇒ 2a = 9 ⇒ a = 9/2

(1) − (2) ⇒ −2b = −1 ⇒ b = ½

Answer a=9/2

b=1/2

Here the above solved problems will help you in your academics. Let me know your views on this and if you have few unsolved problems which you want me to discuss it with you, write back and we will work it on together.