If 7 times the square of an integer is added to 5 times the integer, the result is 2. Find the integer.
This is a quadratic equation. To get it into standard form, we subtract 2 from each side:
7x^2 + 5x - 2 = 2 - 2
7x^2 + 5x - 2 = 0
Type this problem into our search engine, and we get two solutions:
Let's check our work by plugging x = -1 into the quadratic:
7x^2 + 5x - 2 = 0
7(-1)^2 + 5(-1) - 2 ? 0
7(1) - 5 - 2 ? 0
0 = 0
So we verified our answer, x = -1.
- Let the integer be "x".
- Square the integer: x^2
- 7 times the square: 7x^2
- 5 times the integer: 5x
- Add them together: 7x^2 + 5x
- The result is means an equation, so we set 7x^2 + 5x equal to 2
This is a quadratic equation. To get it into standard form, we subtract 2 from each side:
7x^2 + 5x - 2 = 2 - 2
7x^2 + 5x - 2 = 0
Type this problem into our search engine, and we get two solutions:
- x = 2/7
- x= -1
Let's check our work by plugging x = -1 into the quadratic:
7x^2 + 5x - 2 = 0
7(-1)^2 + 5(-1) - 2 ? 0
7(1) - 5 - 2 ? 0
0 = 0
So we verified our answer, x = -1.