This is a science question sryjoe was heating a test tube when it cracked. what could have caused it to crack? a. he held the test tube directly over the flame for too longb. he did not add water to the test tubea or b, explain tks

A is more likely. Heating something to fast and for too long can cause stress on the glass causing it to crack. Water wouldn’t have effected it

x² + 3x + 7 = 0       [ax² + bx + c]

a = 1

b = 3

c = 7

quadratic formula:

    (+/- is this ±)

plug in the numbers into the variables

your answer is a

step-by-step explanation:

the ratio of red paint to blue paint is always 9/7. that means that, whatever x's value, (4x+12)/(4x-4) has that same ratio. so, set up an equation and cross-multiply to solve for x:

9/7 = (4x+12)/(4x-4)

9(4x-4) = 7(4x+12)

36x - 36 = 28x + 84

8x - 36 = 84

8x = 120

x = 15