Respuesta :
Answer:
x = 4/7 or x = 5
Step-by-step explanation:
Step 1: Add to 3 to both sides
- [tex]7x^2-39x+17+3=-3+3[/tex]
- [tex]7x^2-39x+20=0[/tex]
Step 2: Factor by grouping
This equation is in the form ax² + bx + c = 0. Since there are no terms that multiply to 20 and add to -39, we have to find terms that multiply to a (7) * (20) and add to -39.
- Factors of 140: 1, 2, 4, 5, 7, 10, 14, 20, 28, 35, 70, and 140
- -35 x -4 = 120, and -35 - 4 = -39. Thus, the two terms are -35 and -4.
Now, we split -39x into -35x and -4.
- 7x^2 - 35x - 4x + 20.
- (7x² - 35x) + (-4x + 20)
Next, we factor each expression in the parentheses. After that, we put the terms outside the parentheses together. Reminder, the terms inside the parentheses should be the same.
- [tex]7x(x-5)-4(x-5)[/tex]
- [tex](7x-4)(x-5) = 0[/tex]
Step 3: Solve for x using 7x - 4 = 0 and x - 5 = 0.
- [tex]7x-4=0[/tex]
- [tex]7x-4+4=0+4[/tex]
- [tex]7x=4[/tex]
- [tex]7x/7 = 4/7[/tex]
- [tex]x= 4/7[/tex]
or
- [tex]x-5=0[/tex]
- [tex]x-5+5=0+5[/tex]
- [tex]x=5[/tex]