Solve 9(x + 1)^2 = 144

Question

asked Sep 21, 2020 49.1k views

2 Answers

Kaifei · Answer 1 · 2020-09-21T19:39:53+0000

Answer:

x = 3

x = -5

Explanation:

(9)(x+1)(x+1) = 144

(9)(x²+2x+1) = 144

9x²+18x+9 = 144

9x²+18x = 135

x²+2x = 15

x(x+2) = 15

x = 3

x= -5

Ach · Answer 2 · 2020-09-25T10:25:21+0000

Answer:
$x_1=3\\x_2=-5$

Explanation:

Divide boht sides of the eqeuation by 9:

$(9(x+1)^2)/(9)=(144)/(9)\\\\(x+1)^2=16$

Remembert that:

(a+b)^2=a^2+2ab+b^2

Then, applying this, you get:

$x^2+2(x)(1)+1^2=16\\x^2+2x+1=16$

Subtract 16 from both sides:

$x^2+2x+1-16=16-16\\x^2+2x-15=0$

Factor the quadratic equation. Find two numbers whose sum be 2 and whose product be -15, then:

$(x-3)(x+5)=0\\x_1=3\\x_2=-5$