|x^2+7x|=4x+10 equation
The teacher will be very surprised to see your correct solution 😉
The solution
Detail solution
For every modulo expressions in the equation
allow cases, when this expressions ">=0" or "<0",
solve the resulting equation.
1.
$$x^{2} + 7 x \geq 0$$
or
$$\left(0 \leq x \wedge x < \infty\right) \vee \left(x \leq -7 \wedge -\infty < x\right)$$
we get the equation
$$- 4 x + \left(x^{2} + 7 x\right) - 10 = 0$$
after simplifying we get
$$x^{2} + 3 x - 10 = 0$$
the solution in this interval:
$$x_{1} = -5$$
but x1 not in the inequality interval
$$x_{2} = 2$$
2.
$$x^{2} + 7 x < 0$$
or
$$-7 < x \wedge x < 0$$
we get the equation
$$- 4 x + \left(- x^{2} - 7 x\right) - 10 = 0$$
after simplifying we get
$$- x^{2} - 11 x - 10 = 0$$
the solution in this interval:
$$x_{3} = -10$$
but x3 not in the inequality interval
$$x_{4} = -1$$
The final answer:
$$x_{1} = 2$$
$$x_{2} = -1$$
Sum and product of roots
[src]
$$-1 + 2$$
$$1$$
$$- 2$$
$$-2$$
$$x_{1} = -1$$
$$x_{2} = 2$$