Show that 5x²+2x-3 can be written in the
form |x+1/5| < 4/5 Hence, solve
the inequality
5x²+2x-3< 0

5x² + 2x - 3 < 0

5x² + 2x < 3

x² + 2/5 x < 3/5

Complete the square on the left side:

x² + 2/5 x + 1/25 - 1/25 < 3/5

(x + 1/5)² - 1/25 < 3/5

(x + 1/5)² < 16/25

Take the square root of both sides, keeping in mind that √(x²) = |x| for all x.

√((x + 1/5)²) < √(16/25)

|x + 1/5| < 4/5

This means

-4/5 < x + 1/5 < 4/5

-1 < x < 3/5

nada

step-by-step explanation:

starting with:    

5 + x - 12 = 2x - 7   

5 + x - 12 - x = 2x - 7 - x (subtract x from both sides)   

5 - 12 = x - 7 (combine and cancel x's from both sides)   

5 - 12 + 7 = x - 7 + 7 (add 7 to both sides)   

0 = x (add numbers together on both sides)       

so in order for the equation to be true, x must be 0.   

trying x = -0.5   

5 + x - 12 = 2x - 7 (original equation)   

5 + -0.5 - 12 = 2(-0.5) - 7 (plug in value of x)   

5 + -0.5 - 12 = -1 - 7 (did multiplication)   

-7.5 = -8 (did addition on both sides)       

since -7.5 is obviously not equal to -8, the value of -0.5 for x is wrong.   

trying x = 0   

5 + x - 12 = 2x - 7 (original equation)   

5 + 0 - 12 = 2(0) - 7 (plug in value of x)   

5 + 0 - 12 = 0 - 7 (did multiplication)   

-7 = -7 (did addition on both sides)       

since -7 equals -7, that demonstrates that the value of 0 for x is correct.   

trying x = 1   

5 + x - 12 = 2x - 7 (original equation)   

5 + 1 - 12 = 2(1) - 7 (plug in value of x)   

5 + 1 - 12 = 2 - 7 (did multiplication)   

-6 = -5 (did addition on both sides)       

since -6 is obviously not equal to -5, the value of 1 for x is wrong.