Solving Quadratic Equations using Factoring - Examples, Exercises and Solutions

Solve x:

$5(x+3)=0$

We open the parentheses according to the formula:

$a(x+b)=ax+ab$

$5\times x+5\times3=0$

$5x+15=0$

We will move the 15 to the right section and keep the corresponding sign:

$5x=-15$

Divide both sections by 5

$\frac{5x}{5}=\frac{-15}{5}$

$x=-3$

$-3$

Solve for x:

$7(-2x+5)=77$

To open parentheses we will use the formula:

$a(x+b)=ax+ab$

$(7\times-2x)+(7\times5)=77$

We multiply accordingly

$-14x+35=77$

We will move the 35 to the right section and change the sign accordingly:

$-14x=77-35$

We solve the subtraction exercise on the right side and we will obtain:

$-14x=42$

We divide both sections by -14

$\frac{-14x}{-14}=\frac{42}{-14}$

$x=-3$

-3

Solve for x:

$-3(\frac{1}{2}x+4)=\frac{1}{2}$

We open the parentheses on the left side by the distributive property and use the formula:

$a(x+b)=ax+ab$

$-\frac{3}{2}x-12=\frac{1}{2}$

We multiply all terms by 2 to get rid of the fractions:

$-3x-12\times2=1$

$-3x-24=1$

We will move the minus 24 to the right section and keep the corresponding sign:

$-3x=24+1$

$-3x=25$

Divide both sections by minus 3:

$\frac{-3x}{-3}=\frac{25}{-3}$

$x=-\frac{25}{3}$

$-\frac{25}{3}$

Solve for x:

$8(x-2)=-4(x+3)$

To open parentheses we will use the formula:

$a(x+b)=ax+ab$

$(8\times x)+(8\times-2)=(-4\times x)+(-4\times3)$

We multiply accordingly

$8x-16=-4x-12$

In the left section we enter the elements with the X and in the right section those without the X, remember to change the plus and minus signs as appropriate when transferring:

$8x+4x=-12+16$

We solve accordingly

$12x=4$

We divide both sections by 12

$\frac{12x}{12}=\frac{4}{12}$

We reduce and obtain$x=\frac{4}{12}=\frac{1}{3}$

$\frac{1}{3}$

Solve for x:

$-9(2-x)=(x+4)\cdot3$

We open the parentheses in both sections by the distributive property and use the formula:

$a(x+b)=ax+ab$

$-18+9x=3x+12$

We move 3X to the left section, and 18 to the right section and maintain the corresponding signs:

$9x-3x=12+18$

We add the terms:

$6x=30$

We divide both sections by 6:

$\frac{6x}{6}=\frac{30}{6}$

$x=5$

5

Solve for x:

$-8(2x+4)=6(x-4)+3$

To open parentheses we will use the formula:

$a\left(x+b\right)=ax+ab$

$(-8\times2x)+(-8\times4)=(6\times x)+(6\times-4)+3$

We multiply accordingly:

$-16x-32=6x-24+3$

Calculate the elements on the right section:

$-16x-32=6x-21$

In the left section we enter the elements with the X and in the left section those without the X, remember to change the plus and minus signs as appropriate when transferring:

$-32+21=6x+16x$

Calculate the elements accordingly

$-11=22x$

We divide the two sections by 22

$-\frac{11}{22}=\frac{22x}{22}$

$-\frac{1}{2}=x$

$-\frac{1}{2}$

Solve for x:

$-7(2x+3)-4(x+2)=5(2-3x)$

To open parentheses we will use the formula:

$a\left(x+b\right)=ax+ab$

$(-7\times2x)+(-7\times3)+(-4\times x)+(-4\times2)=(5\times2)+(5\times-3x)$

We multiply accordingly:

$-14x-21-4x-8=10-15x$

We calculate the elements in the left section:

$-18x-29=10-15x$

In the left section we enter the elements with the X and in the right section those without the X, remember to change the plus and minus signs as appropriate when transferring:

$-18x+15x=10+29$

We calculate the elements accordingly:

$-3x=39$

We divide the two sections by -3:

$\frac{-3x}{-3}=\frac{39}{-3}$

$x=-13$

-13

Solve for x:

$2(4-x)=8$

0

$3x+5(x+4)=0$

$x=-2.5$

$8a+2(3a-7)=0$

$a=1$

$3(a+1)-3=0$

$a=0$

$5-(3b-1)=0$

$b=2$

$2(x+4)+8=0$

$x=-8$

Solve for y:

$-2(-4+y)-y=0$

$y=2\frac{2}{3}$

Solve for X:

$\frac{1}{2}(x+3)=0$

3-