Here is another post with two of the same questions on it:
http://web2.0calc.com/questions/what-is-the-exact-value-of-x-urgent-help
1. y = log(7x + 3) - 2
To find the x-intercept, plug in 0 for y and solve for x .
0 = log(7x + 3) - 2 Add 2 to both sides of the equation.
2 = log(7x + 3) Exponentiate both sides with a base of 10 .
102 = 10log(7x + 3)
100 = 7x + 3 Subtract 3 from both sides.
97 = 7x Divide both sides by 7 .
97/7 = x
the x-intercept = 97/7 ≈ 13.86
To find the y-intercept, plug in 0 for x and solve for y .
y = log(7(0) + 3) - 2 Simplify.
y = log(3) - 2 Plug this into a calculator to get...
y ≈ -1.52
the y-intercept ≈ -1.52